Teaching Case

A 38-year-old pregnant woman, with history of prior uncomplicated c-section, underwent a c-section at 41 weeks. The procedure was uneventful. Fever was noticed on the third post-operative day. Trans-abdominal ultrasound revealed intrabdominal free fluid and CT suggested peritonitis (Figure 1). Antibiotics were started, but complaints persisted.

Due to the persistence of symptoms, even with antibiotics, an abdominopelvic CT was repeated on the 12th day post-c-section. Several collections were identified in the abdominal cavity, namely peri-hepatic, peri-umbilical, pouch of Douglas and abdominal wall (Figure 2). A suspicious collection with gas content was noted between the anterior aspect of the uterus and the anterior abdominal wall, extending to the paracolic gutter, measuring 2,2 x 18 cm (Figure 2). The collection insinuated itself towards the anterior region of the uterus, appearing to communicate with the endometrial cavity through the caesarean scar. There were gas bubbles in the endometrial cavity at the level of the anterior uterine isthmus (Figure 3). These findings are suggestive of an incisional uterine dehiscence.

A laparotomy was performed, and the c-section scar dehiscence was confirmed. The wound was surgically repaired. Follow-up abdominopelvic CT revealed partial resolutions of collections (Figure 4).

Postpartum uterine dehiscence is defined as a separation of the incision line after c-section with disruption of the endometrium and myometrium with intact uterine serosa [1].

This is a rare post-partum complication, with a frequency between 0.06% and 3.8% [2]. Despite its low incidence, this complication is a relevant maternal mortality cause. Besides, there is a tendency for increasing detection with the current increase in the rates of c-sections performed [3]. Some risk factors to consider include diabetes, emergency surgery, infection, multiparity, suture technique, haematoma on the uterine incision line, and retrovesical haematoma [2,4].

Clinical presentation of uterine dehiscence may be subtle, with nonspecific abdominal pain, which can easily be misinterpreted, leading to a late diagnosis. Therefore, this differential diagnosis must be kept in mind, with imaging playing a decisive role in its establishment.

Ultrasonography (US) should be used as the first-line imaging modality to evaluate postpartum complications and may allow the assessment of the uterine incision. Despite its capability to identify indirect signs of dehiscence, such as free fluid, collections or haematomas, US does not allow to differentiate uterine dehiscence from the normal appearance of the uterine incision [2,5–7]. This is the case of our patient, in which a trans-abdominal US on the third day after c-section revealed free fluid in the abdomen but did not distinguish any defects or collections in the caesarean scar.

CT scans with multiplanar reconstructions can provide additional information, being widely used in the emergency setting, especially when US is indeterminate, as in the presented case. However, the CT performed on the third day post-op (Figure 1) confirmed free fluid in the abdomen, with no adjacent collections or signs of wall fragility. We believe that the lack of specific CT findings in this context may be related to its low sensitivity to detect early findings. Moreover, most reported cases describe imaging findings between 11 days and 12 weeks after surgery [8].

Magnetic resonance imaging (MRI) has a better diagnosis yield than CT, enabling the visualisation of the cervix and the uterine anterior wall simultaneously, allowing to evaluate the integrity of serosa with better resolution [9–10]. However, due to its low availability and its being time-consuming, MRI is only performed in highly suspicious circumstances, when US and CT are inconclusive.

In our case, the CT at 12 days post-op (Figure 2) enlightened the accurate diagnosis of uterine dehiscence.

Written informed patient consent for publication has been obtained.