Analgesic requirements and postoperative recovery after scheduled compared to unplanned cesarean delivery: a retrospective chart review

Introduction 

Studies examining the efficacy of various analgesics and anesthetics on postoperative pain following cesarean delivery conventionally use the scheduled cesarean delivery population.[1], [2], [3], [4], [5], [6] This convention limits the number of subjects available for post-cesarean pain studies. If pain, analgesic requirements and/or side effect profiles are similar and paralleled in the two populations, then this would significantly increase the number of subjects available for post-cesarean analgesia studies. However, if the populations differ significantly in their pain experience, then specific analgesic regimens for each population may prove useful. Currently, findings from elective, scheduled cesarean delivery populations are usually extrapolated and applied to unplanned cesarean patients. We are unaware of any studies comparing postoperative analgesic requirements and recovery profiles in women undergoing scheduled cesarean delivery compared to unplanned cesarean delivery following labor.

Most post-cesarean delivery studies follow patients for the first post-partum day.[7], [8], [9] Few studies record analgesia and side effects beyond 48-72h. One study followed patients for longer than 72h post-cesarean but this study was limited to a specific medication profile rather than the generalized postoperative pain experienced and analgesic consumption.10

The aim of this retrospective chart review was to document pain and analgesic consumption for up to five days post-cesarean to observe analgesic requirement during the hospital stay. We compared the recovery characteristics of patients having undergone either scheduled cesarean delivery or unplanned cesarean delivery during labor, reviewed pain perceived and determined analgesic requirement profiles during their hospital stay. We postulated that unplanned cesarean delivery might increase postoperative analgesic requirements compared with scheduled cesarean delivery.

Methods 

Following Institutional Review Board exemption approval, we conducted a retrospective chart review of 200 cesarean deliveries undertaken at Lucile Packard Children’s Hospital, Stanford, California. Lucile Packard Children’s Hospital is a university hospital and tertiary referral center. The hospital performs approximately 5500 deliveries per year with a mean labor epidural analgesia rate of over 80% and an overall cesarean delivery rate of approximately 28%. Study investigators used the hospital’s maternal database to search for 200 consecutive cesarean deliveries that fit the criteria of the study (term, singleton cesarean deliveries with Pfannenstiel incision). We selected 100 patients who had scheduled cesarean delivery under spinal anesthesia and 100 patients who had unplanned cesarean delivery with epidural anesthesia after attempted vaginal delivery between 1st July and 31st August 2004.

At our institution all scheduled cesarean deliveries under spinal anesthesia are performed with hyperbaric bupivacaine 12mg plus intrathecal fentanyl 10μg and preservative-free morphine 200μg. Unplanned cesarean deliveries in laboring patients with epidural catheters in-situ for labor analgesia, are carried out using the epidural catheter. Labor analgesia is maintained with patient-controlled epidural analgesia using 0.0625% bupivacaine with sufentanil 0.4μg/mL. For cesarean anesthesia, a 10-25-mL epidural bolus of 2% lidocaine with epinephrine 1:200000 and bicarbonate 1mEq/10mL is given. After cord clamping, patients receive epidural morphine 4mg. Postoperatively, all patients receive oral ibuprofen 600mg every 6h for 72h. Breakthrough postoperative pain is managed with oral opioid analgesics: oxycodone 5mg with acetaminophen 325mg (Percocet®, Endo Pharmaceuticals, Chadds Ford, PA) and hydrocodone 5mg with acetaminophen 500mg (Vicodin®, Abbott Labratories, North Chicago, IL). Intravenous morphine was available for severe pain or pain not responding to oral opioid analgesics.

Medical charts were reviewed for pain scores (verbal pain scores (VPS 0-10, 0=no pain, 10=worse pain imaginable), consumption of opioids and non-steroidal anti-inflammatory drugs (NSAIDs), time to first analgesic request (min), treatment of side effects pruritus (nausea and vomiting), and length of hospital stay (hours from end of cesarean delivery). Pain scores were taken as an average of all nurse recorded VPS for each 24-h period. All doses of oral oxycodone and hydrocodone were converted to intravenous morphine milligram equivalents using a conversion ratio of 20mg oral oxycodone hydrocodone equivalent to 10mg intravenous morphine, and added to any intravenous morphine consumption to derive the total supplemental opioid analgesic consumption.

Results 

Of the 200 charts selected, 190 were included in the analysis. One scheduled and nine unplanned cesarean charts were excluded because general anesthesia was used or important data were missing. Demographic and obstetric data including age, height, gestational age, number of previous pregnancies and deliveries were similar between the groups (Table 1). There was a statistically significant difference in race among the groups; more Asian women had unplanned cesareans and more Hispanic women had scheduled cesarean deliveries. The scheduled cesarean group, had a history of more previous cesarean deliveries (unsurprisingly), had a slightly higher body mass index, and had more tubal ligations. As expected, the indications for the cesarean delivery were also different in the two groups (Table 2). The main reasons the unplanned group underwent cesarean delivery were failure to progress and a non-reassuring fetal heart rate, while the most common reasons for cesareans in the scheduled group were breech presentation and previous cesarean delivery.

Table 1. Demographic and obstetric data

		Scheduled cesarean delivery (n=99)	Unplanned cesarean delivery (n=91)
	Age (years)	32±6	32±6
	Weight (kg)	83±16	77±19⁎
	Height (cm)	163±8	163±8
	Gestational age (weeks)	38±2	38±3
	Previous cesarean (%)	69%	2%⁎
	Tubal ligation (%)	21%	2%⁎
	Gravida	3 (1-9)	1 (1-10)
	Parity	1 (0-8)	0 (0-3)
	Race
	Caucasian	38	38
	Hispanic	33⁎	17
	Asian	5	11⁎
	Pacific Islander	0	3
	African American	5	3
	Other	18	19

Data are mean±SD, median (range) actual number or percentage.

⁎ P<0.05 between groups.

Table 2. Indications for cesarean delivery

		Scheduled cesarean delivery (n=99)	Unplanned cesarean delivery (n=91)
	Non-reassuring fetal heart rate	0	25⁎
	Cephalopelvic disproportion	0	4
	Failure to progress	0	37⁎
	Unanticipated malposition	0	2
	Other	12	23
	Primary elective	1	0
	Elective repeat	63⁎	0
	Breech/malposition	18⁎	0
	Placenta previa	5	0

Data are numbers of patients.

⁎ P<0.05 between groups.

All patients in the scheduled cesarean delivery group had spinal or combined spinal-epidural anesthesia, except two patients who received epidural anesthesia. All scheduled cesarean patients received intrathecal morphine 200μg except the two patients outlined above who received epidural morphine 4mg. All unplanned cesarean patients received epidural morphine 4mg.

In the five days after surgery, verbal pain scores and daily opioid consumption did not differ significantly between the two groups (Fig. 1, Fig. 2). Time to first analgesic request and overall opioid and NSAID consumption were similar in the two groups (Table 3). Post hoc power analysis indicated the study had 92% power to detect a 30% difference in total postoperative opioid analgesic consumption between the two groups (P <0.05). The scheduled patients were discharged significantly earlier than those who had unplanned cesarean deliveries (Table 3 and Fig. 3). No patient was discharged earlier than 40h postoperatively.

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Fig. 1. Verbal pain scores (0-10; 0=no pain and 10=the worst pain imaginable) on days 1 through 5 as reported by patients following scheduled cesarean (black circle) and unplanned (black square) cesarean deliveries. There were no statistical differences between the groups.

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Fig. 2. Opioid consumption in each 24-h period following scheduled (black circle) cesarean and unplanned (black square) cesarean deliveries. The values are reported in intravenous-morphine equivalents for each postoperative day. The only statistically significant difference between groups occurred on Day 5 (*=significant difference).

Table 3. Analgesic use and length of hospital stay

		Scheduled cesarean delivery (n=99)	Unplanned cesarean delivery (n=91)	P
	Time to first analgesic (min)	585±444	742±588	0.06
	Total opioid consumption (mg)⁎	83±51	95±53	0.07
	Total ibuprofen use (mg)	1921±2319	2118±2326	0.44
	Percentage using NSAIDs in the first 48h post-cesarean	60%	64%	0.48
	Length of hospital stay (h)	100±93	148±187	0.04

Data are mean±SD and percentage as indicated. NSAIDS: non-steroidal anti-inflammatory drugs.

⁎ Intravenous morphine milligram equivalents consumption in 5 days post partum (All doses of oral oxycodone and hydrocodone were converted to intravenous morphine milligram equivalents using a conversion ratio of 20mg oral oxycodone hydrocodone equivalent to 10mg intravenous morphine, and added to any intravenous morphine consumption to derive the total supplemental opioid analgesic consumption). Length of hospital stay was recorded in hours from end of the cesarean delivery.

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Fig. 3. Proportion of patients who underwent scheduled cesarean (black) and unplanned (grey) cesarean deliveries still in hospital at any time point during the 5 postoperative days. (Kaplan-Meier Survival Curve; Log-rank<0.001).

There was no difference between the scheduled and unplanned cesarean delivery groups in side effects requiring intervention. Twenty-two percent of patients received medication for nausea and vomiting and 21% for pruritus, with no significant difference between the groups.

Discussion 

In our study, patients undergoing scheduled and unplanned cesarean delivery experienced similar analgesic recovery profiles as measured by postoperative analgesic consumption, time to first postoperative analgesic request and pain scores for up to five days postoperatively. Our findings suggest that these obstetric populations are comparable and behave similarly after cesarean delivery with regard to postoperative pain.

These results imply that the unplanned cesarean population may be as suitable a pain model as the elective cesarean delivery patient to study pain management strategies. Our findings also demonstrate that alterations in pain management are not required for unplanned compared to elective cesarean deliveries. However, a number of potential limitations and confounders must be considered.

Firstly, the two study populations received different routes and doses of neuraxial analgesia. Patients undergoing scheduled cesarean delivery received intrathecal morphine 200μg whereas patients having unplanned cesarean delivery received epidural morphine 4mg. This 20:1 dose ratio between intrathecal and epidural morphine administration used at our institution has been found to provide similar analgesia after cesarean delivery.[11], [12] Two studies in the elective cesarean population reported equi-analgesia with epidural and intrathecal morphine administered in a dose ratio of 15-30:1.[11], [12] Based on these findings, we feel that the similar pain control found in our scheduled versus unplanned cesarean populations is not confounded by differences in the route and dose of neuraxial analgesia that the patients received.

Secondly, the study was conducted retrospectively and by nature was not as robust as a prospective study. Nevertheless, a retrospective study allowed us to observe analgesic recovery in a real clinical setting and not under study conditions. The protocol confines of a prospective study may affect patient behavior and create inherent bias, which can affect the clinical results. Moreover, we would have expected both study populations to have been subjected to similar confounding influences during their postoperative recovery. Complications such as wound infection were not assessed, but there was no difference in the number of women requiring intervention for pruritus, nausea and vomiting between the study groups.

Thirdly, some of the demographics between the two study populations were, as predicted, different. The scheduled group had more previous cesarean deliveries and underwent concomitant tubal ligation more frequently than did the unplanned cesarean patients. Women who were not expecting to undergo a cesarean delivery would not necessarily have considered their option to have a tubal ligation at the same time or have enough time to consent to the procedure. Tubal ligation may be associated with more pain following cesarean delivery.[13], [14], [15] However, subgroup analysis between patients undergoing cesarean with concomitant tubal ligation and those who underwent cesarean delivery only, revealed no differences in pain and analgesic consumption. Patients undergoing elective cesarean delivery weighed an average 6kg more than the unplanned cesarean patients. Obesity is a known risk factor for cesarean delivery during labor.16 We would not expect these observed small differences in body habitus to have altered patients’ pain thresholds significantly. We observed that more Asian women had unplanned cesareans and more Hispanic women had scheduled cesarean deliveries. This probably represents a sub-group population selection bias within our existing geographic area. These differences in race may have confounded both perceived and treated pain.

The similarities in postoperative pain profiles between study groups may be explained by the surgery itself. Although the study populations required cesarean delivery for different indications, the surgical incision and procedure in each study group were essentially the same; this may outweigh any subtle difference in the circumstances of the cesarean delivery. Due to the retrospective nature of the study, we relied on pain scores that were taken as part of routine care. These pain scores were not timed consistently as would be with a prospective study, so they were averaged for each 24-h period. This methodology may have missed subtle variations within each 24-h period, but the goal of the study was to observe analgesia over a number of days after cesarean delivery. To our knowledge, this is the first study to follow patients daily for 5 days. Our findings show that women experience pain of similar magnitude on days 4 and 5 as in the preceding 72h, although opioid use declined on day 4 and 5 in planned and unplanned cesarean delivery groups.

The scheduled cesarean delivery patients were discharged from hospital approximately two days earlier than those undergoing unplanned cesarean delivery. This is consistent with the findings of Qazi et al.17 Different circumstances of cesarean delivery may inherently involve more complications that can extend hospital stay. Although we did not record the incidence of complications or neonatal outcome, these may explain the differences we observed with the length of hospital stay between the two groups. Patients undergoing scheduled cesarean delivery would not have endured a potentially long trial of labor. Increased exertion, anxiety, and sleep deprivation associated with an unplanned cesarean delivery may have contributed to differences in hospital stay. Sleep loss and anxiety have been shown to affect postoperative recovery.[18], [19] Although fewer patients who underwent scheduled cesarean delivery remained in hospital on postoperative days 4 and 5, among those who were still in hospital pain scores were similar in the two groups.

There was a trend toward an increase in total opioid consumption in the unplanned group, but this difference was small and clinically insignificant as pain scores remained similar. Patients who stayed in the hospital longer than 72h were perhaps experiencing more pain than those who had previously been discharged, but we did not determine reasons for prolonged hospital stays or if pain contributed to it.

Few post-cesarean analgesia studies follow patients beyond the first 24 h postoperatively. Studies that extended data collection to 48-72h show that patients experience peak pain levels on the second postoperative day.[1], [20] These studies used neuraxial morphine with an expected analgesic duration of approximately 24h.[21], [22] In our study we found mean time to first analgesic request was only 10±7 and 12±10h for the scheduled and unplanned cesarean delivery patients respectively. These time intervals were significantly less than predicted from the meta-analysis by Dahl et al. that found a median time to first request for analgesia after a single intrathecal dose of morphine after cesarean delivery to be 27h (range 11-29h).22 There was a trend to a longer duration until first analgesic in the unplanned group. This may be because more unplanned than planned cesarean deliveries occur in the afternoon or evening, following which there are fewer nurses on duty and patients may be asleep.

In conclusion, although prospective studies are needed to confirm these results, our study shows that, in the environment of clinical practice, patients undergoing scheduled compared to unplanned cesarean delivery experience similar pain, use comparable amounts of postoperative analgesics, and have similar times to first request for postoperative analgesia. These results suggest that the non-scheduled cesarean population may be a suitable pain model to study pain management strategies, and that alterations in pain management are not necessary for unplanned compared to scheduled cesarean deliveries. This study demonstrates that significant pain is still experienced on the fourth and first postoperative day.