Uterine dehiscence, albeit uncommon, is a relatively more common event than uterine rupture, and results from uterine scar rupture, while the overlying visceral peritoneum remains intact and the fetus, umbilical cord, and placenta remain in the uterine cavity. The rate of uterine wound dehiscence at the time of repeat, elective lower segment cesarean delivery (LSCD) is not well established. Risk factors include number of previous LSCDs, arrested labor during the first stage, preterm delivery, fetal macrosomy, and augmented labor.1,2 To our knowledge, spontaneous uterine dehiscence during positioning and performance of spinal anesthesia has never been reported; however, it should be considered as part of the differential diagnosis of unusual back pain while establishing spinal or epidural block. We describe a case of severe unusual back pain during the performance of subarachnoid block for elective LSCD, with the diagnosis of uterine dehiscence being made during surgical dissection.
The patient was contacted and has kindly given both verbal and written consent for publication of this case.
Our patient was a 37-year-old healthy gravida 4, para 2 at 38 weeks gestation with a singleton pregnancy, and elective LSCD and bilateral tubal ligation were planned. The current pregnancy had been complicated with vaginal spotting during the second trimester and hyperemesis both of which resolved with conservative management. Routine ultrasound at 32 weeks gestation did not report any uterine wall abnormality. Her obstetric history included 2 LSCDs performed under spinal anesthesia, both of which were uneventful. She had gestational diabetes in 2007 for which she required insulin treatment. Her prepregnancy body mass index was 24.5 kg/m2. Her previous surgery included a gastric sleeve and dilation and curettage. At this presentation, and after consultation with the anesthesiologist, the patient chose to have the elective LSCD under spinal anesthesia.
Spinal anesthesia was performed under sterile conditions with the patient sitting and rolled forward. One percent lidocaine was infiltrated subcutaneously, and a 25-gauge Sprotte spinal needle was inserted into the L3/L4 lumbar interspace. Left flank pain was described and the needle was repositioned, with resolution of the pain. Clear cerebrospinal fluid flowed freely and a mixture of 2.4 mL of 0.5% hyperbaric bupivacaine (12 mg bupivacaine) and 20 mcg of fentanyl was injected into the subarachnoid space. After completion of the spinal block, and as the patient was being repositioned with left uterine tilt, she complained of severe left-sided back pain. The pain was described as excruciating and was very distressing to the patient; she had never experienced anything similar. The pain reported originated from the back, was a strong sharp and sudden-onset pain, and radiated to the left flank and front of the abdomen. She was given 25 mcg of IV fentanyl for supplementary analgesia.
The ampules used for the spinal anesthetic were cross-checked, and it was confirmed that the correct medications had been drawn up and injected into the subarachnoid space.
Initial observations revealed a systolic blood pressure of 89 mm Hg with a heart rate of 59 beats per minute. This was treated with 6 mg of ephedrine. The left flank pain decreased as the spinal anesthetic block became established and extended to a higher level. An ongoing arterial blood pressure decrease was treated with a further 6 mg of ephedrine and a fluid bolus of 500 mL of Hartmann solution resulting in a sustained blood pressure to >100 mm Hg systolic.
The patient was positioned on the operating table with left uterine tilt. After incision and dissection through the layers of the anterior abdominal wall and on entry into the abdomen, a full thickness dehiscence of the anterior uterine wall with herniation of the amniotic sac through the uterine wall was observed (Fig. 1). The dehisced anterior wall of the uterus was noted to be thin-walled with minor bleeding along the line of the dehiscence. The amniotic sac was opened, a live baby girl was delivered, and the placenta was removed without complication. Apgar scores were 9 and 9 at 1 and 5 minutes, respectively. The baby weighed 3330 g. The patient was hemodynamically stable for the remainder of the procedure and reported no further concerns. The full thickness dehiscence was repaired by the obstetrician, and the surgery was completed uneventfully.
The patient was followed up the next day and no further back pain was reported. She had an uneventful recovery and was discharged home on day 4 postoperatively. Sudden uterine dehiscence at the time of performing the spinal block was the most likely explanation for the sudden severe back and abdominal pain she experienced.
Uterine dehiscence and potentially uterine rupture are well-recognized complications of previous LSCD and a major reason for elective repeat LSCD in preference to a trial of labor after previous cesarean delivery. Deficient cesarean scars are relatively common, with transvaginal ultrasound in gynecological patients revealing 19% of women who had undergone previous LSCD had deficient scars.3 Presumably the factors associated with uterine dehiscence, such as a macrosomic fetus or augmented labor, are factors that increase the intrauterine pressure, and this in combination with a thin-walled uterus or scar defect ultimately contributes to dehiscence or rupture. In this case, it is likely that positioning during the spinal blockade; sitting and rolled forward, and then swinging the legs up after completion of the subarachnoid block caused a transient increase in intrauterine pressure that ultimately led to dehiscence. Interestingly, it has been shown with intrauterine pressure transducers that the highest baseline pressure during labor is obtained with the patient in the sitting position.4
Reassuringly, the literature would suggest that uterine dehiscence without extrusion of the fetus into the maternal abdomen does not result in increased maternal or neonatal mortality or morbidity.5 Uterine dehiscence may present with a range of mild symptoms or be an incidental finding at the time of repeat LSCD. Logically, uterine dehiscence would predispose to the more catastrophic scenario of complete uterine rupture, which, if not diagnosed and managed emergently can result in significant maternal and perinatal mortality and morbidity.6
This case acts as a reminder that potential complications during obstetric anesthesia can occur at any point before the delivery of the baby. Uterine dehiscence should be included as a differential diagnosis of unusual abdominal pain during performance and positioning of the parturient. Additionally, if a uterine defect is known to be present, it may be prudent to avoid the extremes of spinal flexion and/or the sitting position during performance of the subarachnoid block.
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