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ORIGINAL RESEARCH |
From RAND, Santa Monica, California; Department of Obstetrics and Gynecology, Brown University School of Medicine/Women & Infants Hospital, Providence, Rhode Island; and the Department of Medicine, University of California Los Angeles School of Medicine, Los Angeles, California.
Address reprint requests to: Deidre Spelliscy Gifford, MD, MPH, Department of Obstetrics and Gynecology, Women and Infants Hospital, 101 Dudley Street, Providence, RI 02905, E-mail: dgifford{at}wihri.org
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Abstract |
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Methods: We reviewed medical records and did a postpartum telephone survey to collect data from 733 women who delivered full-term, nonbreech infants by unplanned cesarean between March 1993 and February 1994. These were a subset of 2447 births sampled at delivery from 30 hospitals in Los Angeles County and Iowa. We measured the proportion of unplanned cesareans done for lack of progress in labor, the cervical dilatation at the time of cesarean, length of the second stage, and slope of the active phase among the women. We estimated the proportion of these cesareans that conformed to the ACOG criteria for the diagnosis of lack of progress.
Results: Lack of progress was a reason for 68% of unplanned, vertex cesareans. At least 16% of the subjects who had cesareans for lack of progress were in the latent phase of labor according to ACOG criteria. The second stage was not prolonged in 36% of the women who delivered at 10 cm.
Conclusion: Lack of progress in labor is a dominant reason for cesarean delivery. Many cesareans are done during the latent phase of labor, and in the second stage of labor when it is not prolonged. These practices do not conform to published diagnostic criteria for lack of progress.
After repeat cesarean, lack of progress in labor (also known as dystocia or failure to progress) is the second most common reason for cesarean delivery in the United States, accounting for 30% of nearly one million cesareans performed annually.1 Because many repeat cesareans are done in pregnancies subsequent to primary cesareans done for lack of progress, an estimated 50–60% of all cesareans may be directly or indirectly related to this diagnosis.2 The proportion of women diagnosed with lack of progress has more than tripled, from 3.8% in 1970 to 11.6% in 1989.3 Although there is currently debate about how far the cesarean rate can be lowered safely, previous efforts to reduce cesarean delivery rates have concentrated on increasing vaginal births after cesarean (VBAC)4,5 and reducing cesarean deliveries for lack of progress.6,7
ACOG has published several documents specifying diagnostic criteria for abnormal labor patterns and guidelines for proceeding to cesarean delivery for lack of progress.8–11 These criteria are found in the Technical Bulletins, educational aids to practicing physicians distributed to all ACOG Fellows. The criteria were subsequently reiterated in the document Quality Assessment and Improvements in Obstetrics and Gynecology, published in 1994 and distributed to all Fellows at that time.12 To explore the degree of conformity between published diagnostic criteria for lack of progress and the criteria used in actual clinical practice, this study compared the labor characteristics of women who were delivered by cesarean for lack of progress with the ACOG criteria.
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Materials and Methods |
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Deliveries were sampled to ensure that half of the sample had cesarean and half had vaginal delivery; half of each of these groups were first-time deliveries and half were second-time deliveries. Within each hospital, we collected data from labor logs or equivalent sources to assess whether parity was 1 or 2 (including the study delivery), whether prior cesareans had been done, and whether the study delivery was by cesarean. We then were able to assign women to one of six delivery subtypes: primiparas with vaginal deliveries, primiparas with cesareans, repeat vaginal delivery, VBAC, repeat cesarean, and cesarean after vaginal delivery. Although our goal at each hospital was to include women from each subtype in direct proportion to the actual distribution of the subtypes in each hospital, the distribution of delivery subtypes in the sample did not reflect the actual distribution of delivery subtypes within each hospital. To account for hospital-specific discrepancies, we used a weighted analysis. We assigned weights to each woman in a way that allowed her to represent the prevalence of her delivery subtype for her hospital. For example, a gravida 2, para 2 woman with a primary cesarean delivery (relatively rare in most hospitals) would receive a weight less than one in each hospital where women with that delivery subtype represented a greater proportion of the sample deliveries than of actual deliveries in that hospital. The weights were constructed so that each hospital contributed in proportion to its sample size. The weighting ensured that less prevalent delivery subgroups (eg, VBAC, cesarean after vaginal delivery) did not contribute more heavily than justified given their relative rareness in the eligible population of deliveries, and each hospital contributed in proportion to the amount of information collected there.
Subjects were then selected from this larger sample. Women whose infants were breech and whose cesareans were planned were excluded from the analysis. The remaining subjects had vertex presentations and intended to deliver vaginally at labor onset. From this sample, we selected all women delivered by cesarean.
To develop a sample of standard-risk pregnancies, we selected women from the labor and delivery logs with the following criteria: at least 18 years of age, English speaking, no more than para 1, not using insulin, without eclampsia or using prepregnancy medication for hypertension, and delivered of singleton infants weighing between 2500 and 4500 g without major congenital anomalies. Mother-infant pairs were excluded if the mother needed more than 7 consecutive days of bed rest during the study pregnancy or if the infant was hospitalized more than 3 weeks after birth, died during the birth hospitalization, or was given up for adoption. This was done to ensure a sample with homogeneous health status and to allow us to collect relevant material from mothers during a postpartum, postdischarge telephone survey.
Postpartum in-hospital interviews confirmed eligibility criteria, language abilities, parity, and prepregnancy and pregnancy inclusion criteria. Data on demographics, insurance coverage, obstetric history, prenatal and intrapartum care, fetal presentation, and maternal and infant outcomes were derived from labor and delivery birth logs, a 45-minute postpartum telephone survey at 4 or 8 weeks postpartum depending on random assignment, and maternal and infant medical records. Medical record abstraction was done by 19 nurses who were given 44 hours of training and monitoring. Records were subsequently reviewed a second time by another nurse and a physician. Interrater reliabilities were measured with item-level kappa scores.
A cesarean delivery was considered planned if the medical record indicated that the decision to deliver by cesarean was made before the delivery admission or if the mother answered affirmatively to the survey question that she ". . . found out for sure that she was going to have a cesarean before she was admitted to the hospital for her delivery." Diagnoses related to progress in labor were abstracted from the physicians’ notes in each record. Data on whether diagnoses were explicitly stated to be reasons for cesarean were also collected from the physicians’ notes. Women were considered to have had a cesarean for lack of progress if their medical records used any of the following terms to describe the reason for the cesarean: dysfunctional, prolonged, protracted, or unspecified long labor; cephalopelvic disproportion; failure to progress; fetal pelvic disproportion; malposition; prolonged or protracted first stage of labor; prolonged or protracted latent phase of labor; prolonged or protracted active phase of labor; arrest of dilation; secondary arrest of dilation; prolonged or protracted second stage of labor; arrest of descent; or deep transverse arrest. Women whose cesareans were done for "failed induction" were included only if their records also noted one of the above conditions to be a reason for cesarean.
Using this information, we defined a group of women who had unplanned cesareans and who had a diagnosis of lack of progress in labor noted as a reason, but not necessarily the only reason, for the cesarean. In many cases, other reasons for cesarean were also present. Because we did not examine the other reasons cited for cesarean, we did not draw conclusions about the appropriateness of the cesarean deliveries in this study. However, lack of progress was listed as a reason for cesarean in all cases, so we assume that it contributed at least in part to the decision to operate. We also assumed that the diagnostic criteria for lack of progress in labor did not change depending on the presence or absence of other diagnoses.
After defining a group of women with unplanned cesareans and a diagnosis of lack of progress that was at least one reason for cesarean, we looked for evidence of abnormal labor patterns. The following data were abstracted from the medical record to define an abnormal labor pattern: time of labor onset, time and cervical dilatation at the first examination done during the delivery admission, time and cervical dilatation at the first examination done at 5 cm or more dilatation, time of complete cervical dilatation, time and cervical dilatation just before cesarean or instrumental vaginal delivery (9.5 cm was substituted when examination indicated that dilation was "rim"), and time of delivery.
Using the data on the course of labor, we calculated the change in cervical dilation per hour from 4 cm to 10 cm, or to delivery if cesarean was done before 10 cm (ie, slope of the active phase); and time from 10 cm dilatation to delivery (ie, length of the second stage).
Table 1
shows the diagnostic criteria for several labor abnormalities derived from documents published by ACOG. To confirm the diagnosis of lack of progress, ACOG recommends that women be in the active phase of labor (defined in Table 1) and show no change in cervical dilatation or descent of the fetal presenting part for at least 2 hours.8,9 We assessed whether women had entered the active phase of labor, as defined by cervical dilatation at the last examination before cesarean delivery.
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Regarding a prolonged second stage of labor, ACOG states10,11:
When the following times are exceeded without continuing progress, the risks and benefits of allowing labor to continue should be assessed and operative delivery considered: Nulliparous: 3 hours with a regional anesthetic or 2 hours without a regional anesthetic. Parous: 2 hours with a regional anesthetic or 1 hour without a regional anesthetic.
By calculating the time from the examination at 10 cm to delivery, we were able to determine whether women who had cesareans for lack of progress in the second stage met these criteria for a prolonged second stage.
Using the diagnostic standards described earlier and our observations on the course of labor, we asked the following questions about each woman who had a cesarean for lack of progress: 1) Was she in the active phase of labor at the time of cesarean? 2) If she was in the active phase of labor, did she have evidence of a protraction disorder? and 3) If her cesarean was done at 10 cm dilatation, was there evidence of a prolonged second stage?
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Results |
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To explore the comparability of our sample to all US births, we compared demographic and clinical characteristics of our study sample and of all US births in 1991. Data on US births were obtained from the National Center for Health Statistics14 (Table 2).
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Table 3 shows the weighted distribution of demographic and obstetric characteristics of the unplanned cesareans. The weighted number of unplanned, vertex cesareans was 337. Lack of progress was cited as a reason for the cesarean in 69% (231 of 337). Unplanned, vertex cesareans for lack of progress represented 9.4% of the 2447 births. The most common terms used to describe lack of progress were "cephalopelvic disproportion," "failure to progress," or "fetopelvic disproportion" (85% of the diagnoses); "prolonged active phase," "arrest of dilation," or "secondary arrest of dilation" (28%); "prolonged second stage," "arrest of descent," or "deep transverse arrest" (24%); and "malposition" (12%). "Abnormal pelvis" was cited as a reason for cesarean in 6% of cases; "prolonged latent phase" or "prolonged first stage" was cited in 3% and 1%, respectively. (These percentages add to greater than 100 because the diagnostic terms are not mutually exclusive.)
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shows the distribution of cervical examinations at the time of cesareans performed for lack of progress, stratified by parity. Twenty-four percent of these cesareans were done at 0–3 cm of cervical dilatation, 53% at 4–9.5 cm, and the remaining 23% at 10 cm.
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). (We have not used the criteria of 3 cm in nulliparas and 4 cm in multiparas because this modification of the definition was published during the latter part of data collection for this study.) We found that 16% of cesareans for lack of progress were done at 0–2 cm of cervical dilatation and 24% were done at 0–3 cm. Fifty-three percent of the cesareans for lack of progress were done at 4–9.5 cm of dilatation (52% of cesareans in nulliparas and 56% of cesareans in multiparas). These subjects were in the active phase of labor by ACOG criteria, and we compared the slope of the active phase in these women with ACOG criteria for protraction disorders. We were able to calculate the slope of the active phase for 80% of these subjects. Of these, 98% met the criteria for protraction disorders. We were unable to calculate the slope of the active phase for 20% of the cesareans for lack of progress done at 4–9.5 cm. In all of these cases, the last examination before cesarean was 4 cm, and we had no other data on cervical examinations in the active phase with which to calculate the slope.
Twenty-two percent of the cesareans for lack of progress were done at 10 cm of dilatation. Comparing the length of the second stage in these subjects with ACOG criteria for prolonged second stage, we found that 36% of these women (45% of nulliparas and 34% of multiparas) did not have a prolonged second stage before their cesareans for lack of progress in the second stage.
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Discussion |
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It seems unlikely that those who perform cesareans are unaware of the criteria for the diagnosis of lack of progress. These criteria have been cited widely in standard texts of obstetrics and in ACOG publications since at least 1976.15–17 Recent work in prenatal care has demonstrated that providers of maternity care follow ACOG standards,18 suggesting that these standards are known to the obstetric community.
Physicians may disagree with current criteria and formulate their own for diagnosing lack of progress. The use of a more relaxed definition of lack of progress in labor than that described by ACOG, as shown in this analysis, may be associated with practitioners’ increasing comfort with the safety of cesarean delivery. Physicians may perceive the risk of cesarean as less than the risk of continuing to observe a labor in the latent phase or the second stage that is not progressing rapidly. If characteristics of the woman, her labor, or the pregnancy cause a physician to worry about the outcome, he or she may be more prone to diagnose lack of progress prematurely. We found that in 51% of the cesareans done for lack of progress, indications for the cesarean other than lack of progress were recorded. The most common of these was terminology referring to nonreassuring fetal status, which was present in 21% of the cesareans done for lack of progress. Other indications, including macrosomia, preeclampsia, and genital herpes, were noted in less than 5% of the cesareans done for lack of progress.
The diagnostic criteria for lack of progress in labor in the ACOG Technical Bulletins are very specific. The 1989 Technical Bulletin8 states that ". . . before the diagnosis of arrest in the first stage of labor is made, . . . the following . . . criteria should be met: 1. The latent phase of labor has been completed, with the cervix dilated 4 cm or more. . . . " Documents published by ACOG after data collection for this study have reiterated this, stating that "a prolonged latent phase of labor is not indicative of dystocia as this diagnosis cannot be made in the latent phase of labor"9 and that women should have completed the latent phase, defined as 3 cm for nulliparas or 4 cm for multiparas, before cesarean delivery for lack of progress.12 It appears unlikely that ambiguity in the definition of the onset of the active phase of labor or questions about the appropriateness of diagnosing lack of progress in the latent phase are explanations for cesareans done in the latent phase.
There may be more ambiguity concerning the second stage of labor. One Technical Bulletin defines prolonged second stage in the context of operative vaginal delivery (ie, forceps or vacuum) (Table 1).10 It states that when the time limits of a prolonged second stage have been exceeded, ". . . the risks and benefits of allowing labor to continue should be assessed and operative delivery considered." Another Technical Bulletin8 defines failure of descent as greater than 1 hour with no descent of the fetal presenting part. Our data show that many of the women who had cesareans for lack of progress in the second stage of labor did not have prolonged second stages according to ACOG criteria. However, our data did not allow us to analyze descent during the second stage, only the total time. These findings suggest that some providers may use failure of descent, which may occur before a prolonged second stage, whereas others may use the total time in the second stage to decide when to diagnose lack of progress.
To examine whether an excessively long latent phase may have prompted these early cesareans for lack of progress, we examined the total time in labor. Although the timing of onset of labor is difficult to determine accurately and often depends on the patients’ or providers’ subjective assessment, we abstracted the time of labor onset that was recorded in the medical record. The average length of labor for nulliparas with cesareans done before 4 cm was 16.0 hours (range 3.0–80.0). For multiparas who had cesareans before 4 cm, the average length of labor was 12.4 hours (range 3.4–23.9), and for all women who had cesareans before 4 cm, the average length of labor was 15.2 hours. The length of labor did not exceed the limits of a prolonged latent phase (greater than 20 hours in nulliparas and 14 hours in multiparas) in 73% of women who had cesareans before 4 cm of dilatation.
Although comparing our sample with the national sample (Table 2) showed little difference in obstetric characteristics, we found a higher prevalence of the diagnosis of lack of progress (46% of cesarean births) than is cited in national statistics (30% of cesarean births).1 This difference is likely due to our sample of women, all of whom had parity of 0 or 1, who would be more likely than those of higher parity to experience labor abnormalities. We compared the prevalence of this diagnosis in women of parity 0 or 1 in the Washington state Birth Events Recording Data19 and found the prevalence in that sample to be similar to ours (48%).
By measuring cervical dilatation just before cesarean delivery, we determined the timing of the cesareans in relation to the course of labor and found that a substantial portion of cesareans for lack of progress occur in the latent phase of labor. Approximately 294,000 cesareans are performed in this country each year for lack of progress in labor.1 If our data are representative of the nation, as many as 70,560 cesareans for lack of progress (24% of 294,000) may be performed in the latent phase. Future research might focus on which labor abnormalities result in poor outcomes and which can be safely observed without posing risks to the mother or fetus.
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Footnotes |
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Received May 7, 1999. Received in revised form September 8, 1999. Accepted September 24, 1999.
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References |
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2. Indications for cesarean section: Final statement of the panel of the National Consensus Conference on Aspects of Cesarean Birth. Can Med Assoc J 1986;134:1348–52.[Medline]
3. Heilbrunn JZ, Park RE. Variations in the use of cesarean sections: Literature synthesis. MR–330. Santa Monica, California: RAND, 1995.
4. Paul RH, Miller DA. Cesarean birth: How to reduce the rate. Am J Obstet Gynecol 1995;172:1903–11.[Medline]
5. Stafford RS. Alternative strategies for controlling rising cesarean section rates. JAMA 1990;263:683–7.[Abstract]
6. Lopez-Zeno JA, Peaceman AM, Adashek JA, Socol ML. A controlled trial of a program for the active management of labor. N Engl J Med 1992;326:450–4.[Abstract]
7. Frigoletto FD, Lieberman E, Lang JM, Cohen A, Barss V, Ringer S, et al. A clinical trial of active management of labor. N Engl J Med 1995;333:745–50.
8. American College of Obstetricians and Gynecologists. Dystocia. ACOG technical bulletin no. 137. Washington, DC: American College of Obstetricians and Gynecologists, 1989.
9. American College of Obstetricians and Gynecologists. Dystocia and the augmentation of labor. ACOG technical bulletin no. 218. Washington, DC: American College of Obstetricians and Gynecologists, 1995.
10. American College of Obstetricians and Gynecologists. Operative vaginal delivery. ACOG technical bulletin no. 152. Washington, DC: American College of Obstetricians and Gynecologists, 1991.
11. American College of Obstetricians and Gynecologists. Operative vaginal delivery. ACOG technical bulletin no. 196. Washington, DC: American College of Obstetricians and Gynecologists, 1994.
12. American College of Obstetricians and Gynecologists. Quality assessment and improvement in obstetrics and gynecology. Washington, DC: American College of Obstetricians and Gynecologists, 1994.
13. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159–74.[Medline]
14. Vital Statistics for the United States. Natality. Hyattsville, Maryland: US Department of Health and Human Services, 1991:1.
15. Dystocia due to abnormalities of the expulsive forces. In: Cunningham FG, MacDonald FC, Gant NF, Leveno KJ, Gilstrap LC, eds. Williams obstetrics. 19th ed. Norwalk, Connecticut: Appleton & Lange, 1993:475–91.
16. O’Brien WF, Cefalo RC. Labor and delivery. In: Gabbe SG, Niebyl J, Simpson JL, eds. Obstetrics: Normal and problem pregnancies. New York: Churchill Livingstone, 1986:351–78.
17. Dystocia due to abnormalities of the expulsive forces. In: Pritchard JA, MacDonald PC, eds. Williams obstetrics. 15th ed. New York: Appleton-Century-Crofts, 1976:656–65.
18. Baldwin LM, Raine T, Jenkins LD, Hart LG, Rosenblatt R. Do providers adhere to ACOG standards? The case of prenatal care. Obstet Gynecol 1994;84:549–56.[Abstract]
19. Jones L, LoGerfo J, Shy K, Connell F, Holt V, Parrish K, et al. STORQS: Washington’s Statewide Obstetrical Review and Quality System: Overview and provider evaluation. QRB Qual Rev Bull 1993;19:110–8.[Medline]
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