Table 1. Characteristics of included studies in the present systematic review.

First author	Year	Total No. of pts	N (stoma)	N (no stoma)	Type of operation	Confirmation of leak	Inclusion criteria	Randomization and allocation	Blinding
Graffner	1983	50	25	25	LAR	Clinical exam, gastrografin enema, proctorectoscopy at 3-month, double-contrast radiography at 1 year	Anastomosis below peritoneal reflection	Sealed envelope	Not possible
Pakkastie	1997	38	19	19	LAR	Clinical exam, radiologic (rectal contrast, CT)	Anastomosis below peritoneal reflection	Sealed envelope	Not possible
Pimentel	2003	36	18	18	LAR	Not reported	Anastomosis ≤4 cm from anal verge	Sealed envelope	Not possible
Matthiessen	2007	234	116	118	LAR	Clinical (digital palpation, inspection of drain), endoscopic or radiologic (rectal contrast study, CT) diagnoses	Anastomosis ≤7 cm anal verge	Sealed envelope	Not possible
Chude	2008	256	136	120	LAR	Clinical exam, radiologic (rectal contrast, CT)	Operable rectal cancer ≤5 cm from anal verge	Sealed envelope	Not possible
Ulrich	2009	34	18	16	LAR	Septic profile, CT scan with rectal filling ± laparotomy	Operable rectal cancers low (4–9 cm) or middle (8–12 cm) from anal verge	Sealed envelope	Not possible
Thoker	2014	78	34	44	LAR	Septic profile, US abdomen/pelvis, CT with oral contrast	Operable rectal cancer 4–12 cm from anal verge	“Systemic” random sampling	Not possible
Mrak	2016	166	94	72	LAR	Clinical diagnoses, confirmed with gastrografin enema ± CT scan ± sigmoidoscopy	Distal border tumors <16 cm from anal verge on rigid rectoscopy	Internet-based randomization	Not possible

LAR, low anterior resection; n, number.