Discussion

Incarceration of the uterus typically occurs by 14–16 weeks of gestational age with rare presentations during the third trimester.3 Common symptoms include dysuria with or without urinary symptoms such as urinary frequency, urinary incontinence or urinary retention. Patients may also complain of either abdominal or suprapubic pain and pelvic discomfort. Other gastrointestinal symptoms due to the compression of rectum such as constipation and/or tenesmus have also been reported.4 ,5 Vaginal bleeding is a not so uncommon presentation in patients with uterine incarceration. Physical examination findings include inability to visualise cervix with speculum and inability to palpate the external os on pelvic examination secondary to severe anterior displacement of cervix behind pubic symphysis. On a rectovaginal examination, a large soft, smooth, non-tender mass can be felt in the cul-de-sac. Because of retroversion, the fundal height may be underestimated than that expected for gestational age. This is partly because of the difficulty in palpating the uterus abdominally. In patients with over distended bladder, the abdomen may appear distended and can interfere with accurately measuring the fundal height. An accurate diagnosis of this condition is made primarily by maintaining a good index of clinical suspicion.

Further confirmation of the diagnosis is via ultrasound examination and MRI. Ultrasound findings in the first half of the pregnancy include cervix that appears thin and elongated as it is pulled anterior to the uterus, a superiorly displaced bladder as the gestational age increases, and a fundus with the fetus positioned posteriorly against the sacrum.4 MRI can be a useful adjunct in cases of diagnostic uncertainty especially during the late second and third trimesters.6 MRI in patients with uterine incarceration characteristically includes freestanding T-shaped multilayer myometrium on sagittal image, small cleft-like cystic lesion between the bladder and the sacculation on axial images corresponding to the elongated cervix and caudal portion of the uterus.7 Additional findings include an inferiorly displaced fundus below the sacral promontory with the displacement of the vagina to the dorsal spine, displacement of the cervix to the ventral and cephalad position along with asymmetric thickening of the posterior uterine wall because of sacculation.7

Maternal complication, such as urinary retention, is a common complication due to the cephalad displacement of the cervix and upper vagina as it lifts the bladder neck and compresses the urethra. This can further lead to hydronephrosis, urinary tract infection and occasionally bladder rupture.5 Incarcerated uterus can also result in peritonitis, sepsis, renal failure and maternal death.8 Fetal complications include spontaneous abortion due to disturbed uterine vascular supply, preterm labour and/or shoulder dystocia.5 Decreased blood flow to the placenta can lead to oligohydramnios and fetal growth restriction.9 It is estimated that fetal demise could be as high as 33% during the second trimester. Rare complications that have been reported include uterine rupture due to uterine wall necrosis, development of cervicovaginal fistula, rectal gangrene and thrombosis. As in the case presented above, fetal heart tones may be affected adversely during physiological uterine contractions. The physician should consider the possibility of ectopic pregnancy, adnexal torsion, appendiceal abscess, posterior fibroid, uterus didelphyus and unconnected rudimentary horn as part of the differential diagnosis. Ultrasound may be a useful tool in excluding the previously noted differentials.

Recommendations for a patient who has been noted to have a retroflexed uterus in the first trimester include bimanual examination or trans-abdominal sonography at 16 weeks to determine whether the fundus has ascended into the abdominal cavity. After 16-week gestation age, the risk of incarceration increases, thus intervention is required. Optimal management of incarceration is between 16 and 20 weeks. Options for intervention include passive reduction, manual reduction, colonoscopic reduction, laparoscopic reduction and laparotomy prior to 20 weeks.10 Passive reduction is attempted by asking the patients to assume the knee–chest position for 10 min at least three times a day for 1 week. If this fails, manual reduction is performed under conscious sedation or regional anaesthesia.11 Nitroglycerin can be given before the procedure to relax the uterus. The patient is placed in dorsal lithotomy position after emptying bladder. Then, mild-to-moderate cephalad pressure is applied to uterine pressure until it is released from the cul-de-sac. Alternately, a finger in the rectum can be applied to increase pressure. If this is unsuccessful, the patient is placed in the knee–chest position and the procedure is repeated. Ultrasound guidance may be helpful. Application of ring forceps to the cervix to provide counter traction to the movement of the fundus has been attempted previously. It has been postulated that the colonoscopy passed through the rectum to the proximal descending colon can generate sufficient external force to dislodge the uterus from the sacral promontory.12 Seubert et al12 reported a case series of five incarcerated uterus refractory to manual reduction who successfully underwent colonoscopic reduction. Additionally, air insufflations with the formation of a loop can have a synergistic effect by creating anterior pressure through the rectal wall on the uterine fundus. Dierick et al7 have reported successful reduction by colonoscopic insufflations without complication in three out of four cases they attempted. Laparoscopic reduction of uterine incarceration is an evolving technique where reduction is achieved after pneumoperitoneum is achieved. Vaginal manoeuvres are initially attempted for manual reduction; if reduction is not achieved, the round ligaments are pulled using atraumatic instruments to free the fundus with concurrent pressure on the fundus from below. Exploratory laparotomy is rarely indicated with the exception of dense adhesion. Postreduction care of the incarcerated uterus includes placement of a Hodge pessary in the vagina for 5–7 days to maintain the upright position.4 ,5 Attempts to manually reduce the uterine incarceration are rarely successful after 20 weeks of gestation. The successful correction of incarceration should be confirmed by ultrasound: assessing fetal well-being and uterine position. If incarceration is noted after 20 weeks of gestation, reduction should be avoided since attempts are unlikely to be successful and can lead to fetal demise.4 The remainder of pregnancy should be monitored for preterm labour, preterm rupture of membranes, oligohydramnios and fetal growth restriction.4 If urinary retention occurs, treatment via self-catheterisation is recommended.

Normal vaginal delivery is contraindicated when the uterus is incarcerated. It has been recommended that C-section should be performed at 36 weeks.9 It is important to ascertain anatomical relationships via MRI as it has high sensitivity in delineating the structures prior to the C-section.11 Owing to severely distorted anatomical relationships in this scenario, during C-sections, a vertical supraumbilical skin incision is recommended rather than low vertical incision. This is performed to avoid supracervical hysterectomy because the bladder, vagina and cervix are positioned ventrally and cephalad in uterine incarceration. After the initial incision to provide adequate exposure of the anatomy, the uterine incision should be performed. Amniocentesis can be performed to facilitate the repositioning uterus in preterm gestations. Recurrence is high in patients with underlying uterine abnormalities or adhesions.13