Approximately 40–45 % of all anastomotic leaks present in this fashion. Patients complain of severe abdominal pain and have a high fever, tachycardia, marked leukocytosis, and signs of generalized peritonitis such as rebound abdominal tenderness and/or rigidity. In these cases, imaging is not required to make a diagnosis of an anastomotic leak. Initial efforts should focus on broad-spectrum antibiotics and aggressive fluid resuscitation.

With the patient in a modified Lloyd-Davies position, an examination under anesthesia will allow for an assessment of the anastomosis, as well as access to the rectum in the event that rectal washout is indicated after abdominal–pelvic exploration. The operative exploration aims to identify the site and extent of leakage, contain further leakage, and aggressively lavage the entire abdominal/pelvic cavity. In cases where the anastomotic disruption and contamination are minimal, pelvic drainage and a proximal diverting stoma may be all that is required. Depending on the long-term plans, a temporary loop ileostomy is a quick option, but the possibility of high output and associated dehydration needs to be taken into consideration in the context of the patient’s age and overall comorbidities. In cases where dehydration is of concern and/or a permanent proximal diversion is envisioned, a left upper quadrant, end-loop (Prasad–Abcarian) colostomy is an option that prevents further contamination, yet affords passage of mucus from the efferent limb should a distal obstruction from a stricture at the anastomosis develop. If the colon is full of feces and therefore a source of further ongoing contamination, a proximal end or end-loop colostomy with distal limb rectal washout is indicated. When creating an end-loop colostomy, great care must be exercised to avoid damage to the marginal artery, which perfuses the afferent limb of the anastomosis, and may be the only source of perfusion in cases where the left colic artery is sacrificed during the initial resection. In cases where a large anastomotic disruption and contamination have occurred, a redo low anterior resection is not a viable option, and these cases are best managed by bringing the afferent limb out as an end colostomy and attempting to suture/staple shut the efferent limb; one should then create a Hartmann’s pouch and assure adequate drainage of the pelvis with drains.

About 30–40 % of patients with an anastomotic leak present with vague abdominal pain, prolonged ileus, mild fever, leukocytosis, and abdominal distension associated with ileus and localized peritoneal signs. Such patients warrant an abdominal pelvic CT scan with oral, IV, and rectal contrast, when possible. When no extravasation of contrast is noted, it is sometimes difficult to distinguish between an anastomotic leak and a postoperative abscess. If the abscess is of reasonable size and walled off, it should be drained percutaneously under radiologic guidance. Success rates for CT-guided placement of a percutaneous drainage catheter are about 80 % [25]. Following successful drainage, some patients go on to develop a chronic enterocutaneous fistula or sinus, which can be managed conservatively. Although most of these patients do not usually require a reexploration, some fail this conservative approach and develop symptoms late after discharge from the hospital. Long-term close follow-up is therefore warranted.

A fistula may be a long-term sequelae in upward of 25–30 % of anastomotic leaks following a low anterior resection. A thorough evaluation includes a careful physical examination as well as optimal contrast imaging with a CT scan and fistulogram in order to delineate a fistula track and rule out distal obstruction. Endoscopy may be helpful in evaluating the orifices of a fistula. If the fistula is well drained and the overall nutritional condition of the patients is adequate, a conservative approach including optimal skin care with a stoma appliance, low suction device, with or without antibiotics, and somatostatin are often sufficient to control the fistula. In cases with a persistent, poorly drained, or intolerable fistula, a surgical approach should be considered. Local therapy with fibrin glue or plugs is rarely effective in this setting. Surgical options include creation of proximal diverting stoma versus primary closure of a rectovaginal fistula via a transanal approach with an advancement flap and temporary stoma or redo low anterior resection.

In addition to the immediate impact on postoperative morbidity and mortality, anastomotic leakage also impacts long-term functional outcome and possibly even long-term prognosis of the rectal cancer patient.