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ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology, University of Arizona Health Sciences Center; and Obstetrix Medical Group, Tucson, Arizona.
Address reprint requests to: Keith M. Harrigill, MD, MPH, Obstetrix Medical Group of Arizona, 5301 East Grant Road, Tucson, AZ 85712; E-mail: harrigill{at}dakotacom.net.
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ABSTRACT |
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 ABSTRACT MATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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METHODS: One hundred ninety-six women undergoing routine cesarean delivery at at least 37 &frac07;weeks’ gestation were prospectively randomized to receive 500–1000 mL of normal saline intraabdominal irrigation versus no irrigation after closure of the uterine incision, but before abdominal wall closure. Data were collected for comparison of demographic factors, intrapartum and postpartum complication rates, and maternal and neonatal outcomes. The primary outcome measure was the combined incidence of maternal morbidity, defined as at least one of the following: postoperative infectious morbidity, postpartum hemorrhage, severe anemia, and urinary retention.
RESULTS: Ninety-seven patients were randomized to the irrigation group and 99 to the control group. The demographic characteristics of the two groups were similar. Thirteen patients (13.1%) in the control group and 14 patients (14.4%) in the irrigation group experienced maternal morbidity (P = .84). There were no statistically significant differences between the groups in estimated blood loss, operating time, incidence of intrapartum complications, hospital stay, return of gastrointestinal function, incidence of infectious complications, or neonatal outcomes.
CONCLUSION: Routine intraabdominal irrigation at cesarean delivery in a low-risk population does not reduce intrapartum or postpartum maternal morbidity.
Cesarean deliveries are potentially morbid procedures, with quoted overall infectious morbidity rates of up to 25%.1 Van Ham2 reported a postpartum hemorrhage rate of 7%, a hematoma formation rate of 3.5%, a urinary tract infection rate of 3%, and a combined postoperative morbidity rate of 35.7% in a high-risk population undergoing cesarean delivery. Strategies to minimize postoperative infectious and other morbidities have included modifications of surgical technique,3–5 changing of gloves,6 methods of placental delivery,6,7 and altering the uterine position during repair of the uterine incision.7
The most successful strategy for reducing post–cesarean delivery febrile morbidity is the administration of antibiotic prophylaxis. In a meta-analysis of 66 randomized clinical trials, Smaill and colleagues at the Cochrane Collaborative8 concluded that the reduction of postoperative endomyometritis by up to 75% justified a policy of routine administration of prophylactic antibiotics to women undergoing both elective and nonelective cesarean deliveries. However, uncertainties persist regarding the selection of the antibiotic agent, the dosing regimen, and the route of administration. For example, Magann and coworkers9 demonstrated significant reductions in postoperative morbidity in patients receiving antibiotic irrigation at the time of cesarean delivery relative to patients receiving saline irrigation and no antibiotics, although Peterson and colleagues10 found that antibiotic irrigation offers no additional benefit when compared with intravenous antibiotics. The occasional practice of irrigating the abdominal cavity with normal saline while using intravenous antibiotics, however, has not been fully evaluated for its independent impact on infectious or other maternal morbidities.
We hypothesized that irrigating the abdominal cavity with normal saline at cesarean delivery in women receiving intravenous antibiotics would not significantly reduce intrapartum or postpartum maternal morbidities when compared with a similar group of women receiving intravenous antibiotics and no irrigation at cesarean delivery.
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MATERIALS AND METHODS |
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All patients were identified at the time of presentation for a scheduled cesarean delivery or when a decision was made to proceed with a nonemergent cesarean delivery after labor. Physicians or research nurses involved with the trial discussed the study with the patient, and a brochure further describing the trial was left with the patient. After allowing time for consideration, the patient was approached again regarding enrollment and all questions were answered. For those patients agreeing to enter the trial, assignment was performed by pulling sequentially numbered opaque envelopes containing computer-randomized individual allocations. This randomization was carried out by research staff before initiation of the study, and the patients were blinded to treatment once assigned.
Patients were randomized to either an irrigation (treatment) or a no-irrigation (control) arm. Those patients in the treatment arm had a Joel-Cohen cesarean delivery with irrigation of the abdominal cavity using 500–1000 mL of warm normal saline after closure of the uterine incision but before closure of the abdominal wall. All blood clots, vernix, and other debris were evacuated from the paracolic gutters, anterior and posterior cul-de-sacs, and under the bladder flap where employed. Patients in the control arm also had a Joel-Cohen cesarean delivery, although without irrigation: All clots, vernix, and other debris were left in place. Both groups underwent standard closure of the abdominal wall, including reapproximation of the rectus muscles and suturing of the rectus fascia with running nonlocking absorbable suture. Prefascial irrigation (irrigation of the subcutaneous tissues superior to the closed fascia) amounts were compared between groups for their potential contribution to maternal outcome. Staples were used for skin closure, and all patients received 1 g of a first-generation cephalosporin intravenously as antibiotic prophylaxis at the time of umbilical cord clamping. There was no significant difference in the type of cesarean delivery performed between groups. The postpartum care for both groups was identical, and included vital signs every 4 hours, discontinuation of the Foley catheter and advancement of diet on the first postoperative day, daily examination of the incision, notation of return of gastrointestinal function, early ambulation, and drawing of a complete blood count 6–24 hours after delivery.
The primary outcome measure was the incidence of maternal morbidity, defined as the presence of at least one of the following: postoperative infectious morbidity (endometritis, cellulitis, urinary tract infection, septic pelvic thrombophlebitis), postpartum hemorrhage, severe anemia, and urinary retention. Endometritis was diagnosed when two of the following were present: abnormally tender uterus on bimanual examination, temperature above 38.0C at more than 24 hours postpartum or greater than 38.5C in the first 24 hours, foul-smelling discharge, and unexplained maternal tachycardia greater than 100 beats per minute. Wound infections were identified by daily visual inspection of the incision, with the clinical diagnosis made when undue tenderness, erythema, discharge, or separation of the incision accompanied maternal fevers. Urinary tract infections were diagnosed when maternal fevers were accompanied by laboratory confirmation of bacteriuria. Septic pelvic thrombophlebitis was identified when postpartum fevers persisted for more than 48 hours on adequate doses of antibiotics and a favorable response to heparin was noted. We defined postpartum hemorrhage as an estimated blood loss of greater than 1000 mL in the 24 hours after delivery, severe anemia as a hematocrit of less than 25 at any point during the hospital stay, and urinary retention as the inability to void more than 4 hours after discontinuation of the Foley catheter on the first postoperative morning. Secondary outcome measures included time to recovery of gastrointestinal function (flatus), length of hospital stay, and changes in the complete blood count parameters. Postoperative care providers were blinded to group assignment to minimize potential bias. Neonatal data such as weight, Apgar scores, arterial pH values, and neonatal intensive care unit admissions were also obtained and compared.
The randomizing physician collected the initial data. Data entry was performed by data technicians who did not participate in the design or execution of the study; these technicians also reviewed the charts of each randomized patient to assess the accuracy of information provided by the treating physician. The senior investigator performed periodic reviews of data entry to ensure completeness and accuracy of information in the computer database.
The data analysis was performed by an investigator blinded to group assignment. An unpaired comparison of means test (Student t test) was performed for continuous outcomes data except for populations with unequal standard deviations, in which case the Mann-Whitney test was substituted. The Fisher exact test was applied for dichotomous outcome variables and nominal outcome variables with more than two categories. Two-tailed P testing was specified, and significance was set at .05 for all tests. Statistical analysis was carried out using Instat 2.01 (Graphpad Software, San Diego, CA) and SPSS 6.1 (SPSS Inc., Chicago, IL).
The sample size was calculated using the Z statistic for comparison of proportions with dichotomous outcomes. We accepted reported combined infectious complication rates of approximately 6%, using the following incidences: endometritis, 2–5%; cellulitis, 2.5–16.1%; and urinary tract infection, 2–16%. The incidence of postpartum hemorrhage has been reported as 10%, producing an overall combined complication rate of 16.5%. Using this expected complication rate and assuming a two-tailed P, an 
of .05, and a ß of .1, a sample size of 96 patients in each arm was indicated to detect a 20% difference in maternal morbidity as a result of the intraabdominal irrigation. Our observed complication rate during the interim analysis at 150 patients was 15%, which did not affect the calculated sample size after adjustment of the level.
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RESULTS |
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) (overall Fisher exact test, P = .74).
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). Patients in the irrigation arm weighed less (82.8 ± 20.0 kg [182.6 ± 44.2 lb] versus 90.1 ± 21.3 kg [198.7 ± 46.9 lb], P = .02), had a more advanced gestational age (39.1 ± 1.4 weeks versus 38.2 ± 1.7 weeks, P = .01), and received more prefascial irrigation (289.7 ± 204.4 mL versus 174.6 ± 134.7 mL, P = .001) than did patients in the control arm. Irrigation added about 1 minute to the duration of the procedure (60 ± 46.5 minutes versus 59 ± 18 minutes, P = .16), a statistically nonsignificant difference given the wide variance in operative times.
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). There were no statistically significant differences in neonatal weight, rate of Apgar scores less than 7 at 1 and 5 minutes, or incidence of neonatal intensive care admissions, as noted in Table 3. |
DISCUSSION |
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In this study, the use of normal saline irrigation of the abdominal cavity in a low-risk population receiving intravenous antibiotics at cesarean delivery did not reduce postpartum morbidities relative to a group of patients receiving intravenous antibiotics and no intraabdominal irrigation. Our initial bias was that intraabdominal irrigation would decrease postoperative febrile morbidity, based on an early study by Kellum and coworkers. In that randomized trial,12 intrauterine saline lavage, both with and without antibiotic, significantly decreased infectious complications in a high-risk population relative to a group of patients receiving no irrigation. However, we chose to evaluate intraabdominal rather than intrauterine irrigation because intraabdominal irrigation usage is prevalent in our community, and to evaluate patients receiving routine intravenous antibiotic prophylaxis.
The impact of prefascial irrigation–lavage performed above the closed fascia but before closure of the skin–on post–cesarean delivery morbidities is poorly documented despite its widespread use in our community. There is experimental evidence in the guinea pig model that normal saline lavage of fresh, heavily contaminated incisions significantly reduces aerobic and anaerobic bacterial counts as well as clinically evident wound infections.13 Given the clean-contaminated nature of cesarean delivery, we recognized that prefascial irrigation may exert an effect on infection rates, and opted to track prefascial irrigation distribution between study groups as a potential confounding variable. Although we did note a differential distribution of prefascial irrigation amounts between groups (289.7 ± 204.4 mL [study] versus 174.6 ± 134.7 mL [irrigation], P = .001), we found no correlation of irrigation quantity to wound infection rate using logistic regression for likelihood ratio testing.
Traditional teaching states that manipulation of the gastrointestinal tract results in prolonged gastrointestinal recovery. Because intraabdominal irrigation and removal of clots involves more manipulation than not irrigating, our bias was that we would find a slow return of normal gastrointestinal functioning in our treatment group. However, we found no significant difference in the time of recovery between groups in this study. One explanation for this unexpected finding may be that we do not routinely perform upper abdomen exploration at the time of cesarean delivery, and therefore our manipulation of the bowel may be less extensive than other physician groups.
One interesting negative finding was the lack of difference in postoperative hemoglobins between groups. One may speculate that leaving behind blood clots at cesarean delivery would lead to resorption of iron and result in higher hemoglobin levels as the clots hemolyze; a complementary hypothesis would state that irrigation would dilute the intraabdominal red cell iron stores and lead to less resorption of iron. Either of these mechanisms would lead to a demonstrably higher postoperative hemoglobin level in the nonirrigation group. We were unable to identify such an effect when examining hemoglobin levels drawn 6–24 hours after delivery, although it is possible that different hemoglobin levels might be observed if testing were repeated at different intervals. We repeated statistical testing for this secondary outcome using paired t testing to compare mean hemoglobin changes within and between groups, and were unable to demonstrate statistical significance using this approach.
We did not assess patient discomfort as the result of our intervention, although it is conceivable that the manipulation involved with irrigating and evacuation of clots might result in additional discomfort. Anecdotally, we noted no increased patient complaints relating to pain. Our reliance on long-acting narcotics (Dura-Morph; Elkins-Sinn Inc., Cherry Hill, NJ) as part of our spinal anesthetic protocol may decrease the reliability of subjective short-term measures of discomfort, at least for the 24-hour period immediately after cesarean delivery. Should this type of study be undertaken again, we would like to see data regarding the impact of irrigation or clot removal on postoperative patient comfort levels.
Our study suggests that intraabdominal irrigation with normal saline at the time of cesarean delivery does not appreciably impact postoperative morbidities such as wound infection, febrile episodes, gastrointestinal recovery, or blood count parameters. In light of these findings, it is difficult to recommend routine normal saline intraabdominal irrigation in a low-risk population receiving prophylactic intravenous antibiotics.
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Footnotes |
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Received March 12, 2002. Received in revised form May 30, 2002. Accepted July 11, 2002.
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REFERENCES |
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2. Van Ham MA, van Dongen PW, Mulder J. Maternal consequences of cesarean section. A retrospective study of intraoperative and postoperative maternal complications of caesarean section during a 10-year period. Eur J Obstet Gynecol Reprod Biol 1997;74:1–6.[Medline]
3. Lyon JB, Richardson AC. Careful surgical technique can reduce infectious morbidity after cesarean section. Am J Obstet Gynecol 1987;157:557.[Medline]
4. Wood RM, Simaon H, Oz AU. Pelosi-type vs. traditional cesarean delivery. A prospective comparison. J Reprod Med 1999;44:788–95.[Medline]
5. Franchi M, Ghezzi F, Balestreri D, Beretta P, Maymon E, Miglierina M, et al. A randomized clinical trial of two surgical techniques for cesarean section. Am J Perinatol 1998;15:589–94.[Medline]
6. Cernadas M, Smulian JC, Giannina G, Ananth CV. Effects of placental delivery method and intraoperative glove changing on postcesarean febrile morbidity. J Matern Fetal Med 1998;7:100–4.[Medline]
7. Magann EF, Washburne JF, Harris RL, Bass JD, Duff WP, Morrison JC. Infectious morbidity, operative blood loss, and length of the operative procedure after cesarean delivery by method of placental removal and site of uterine repair. J Am Coll Surg 1995;181:517–20.[Medline]
8. Smaill F, Hofmeyer GJ. Antibiotic prophylaxis for cesarean section [Cochrane Review]. Cochrane Database Syst Rev 2002;3:CD000933.
9. Magann EF, Dodson MK, Ray MA, Harris RL, Martin JN Jr, Morrison JC. Preoperative skin preparation and intraoperative pelvic irrigation: Impact on postcesarean endometritis and wound infection. Obstet Gynecol 1993;81: 922–5.
10. Peterson CM, Medchill M, Gordon DS, Chard HL. Cesarean prophylaxis: A comparison of cefamandole and cefazolin by both intravenous and lavage routes, and risk factors associated with endometritis. Obstet Gynecol 1990;75:179–82.
11. National Hospital Discharge Survey: Rates of cesarean delivery–United States-1991. MMWR Morb Mortal Wkly Rep 1992;24:285.
12. Kellum RB, Roberts WE, Harris JB, Khansur N, Morrison JC. Effect of intrauterine antibiotic lavage after cesarean birth on postoperative morbidity. J Reprod Med 1985;30: 527–9.[Medline]
13. Badia JM, Torres JM, Tur C, Sitges-Serra A. Saline wound irrigation reduces the postoperative infection rate in guinea pigs. J Surg Res 1996;62:457–9.
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