Abstract: The review includes a total of 42 trials, and 40 of these trials contributed data on 4240 participants. Twenty studies, involving 1918 women, compared clindamycin plus an aminoglycoside (gentamicin for all studies except for one that used tobramycin) with another regimen. When assessing the individual subgroups of other antibiotic regimens (i.e. cephalosporins, monobactams, penicillins, and quinolones), there were fewer treatment failures in those treated with clindamycin plus an aminoglycoside as compared to those treated with cephalosporins (RR 0.69, 95% CI 0.49 to 0.99; participants = 872; studies = 8; low quality evidence) or penicillins (RR 0.65, 95% CI 0.46 to 0.90; participants = 689; studies = 7, low quality evidence). For the remaining subgroups for the primary analysis, the differences were not significant. There were significantly fewer wound infections in those treated with clindamycin plus aminoglycoside versus cephalosporins (RR 0.53, 95% CI 0.30 to 0.93; participants = 500; studies = 4; low quality evidence). Similarly, there were more treatment failures in those treated with an gentamicin/penicillin when compared to those treated with gentamIcin/clindamycin (RR 2.57, 95% CI 1.48 to 4.46; participants = 200; studies = 1). There were fewer treatment failures when an agent with a longer half-life that is administered less frequently was used (RR 0.61, 95% CI 0.40 to 0.92; participants = 484; studies = 2) as compared to using cefoxitin. There were more treatment failures (RR 1.94, 95% CI 1.38 to 2.72; participants = 774; studies = 7) and wound infections (RR 1.88, 95% CI 1.17 to 3.02; participants = 740; studies = 6) in those treated with a regimen with poor activity against penicillin-resistant anaerobic bacteria as compared to those treated with a regimen with good activity against penicillin-resistant anaerobic bacteria. Once-daily dosing was associated with a shorter length of hospital stay (MD -0.73, 95% CI -1.27 to -0.20; participants = 322; studies = 3). There were no differences between groups with respect to severe complications and no trials reported any maternal deaths. Regarding the secondary outcomes, three studies that compared continued oral antibiotic therapy after intravenous therapy with no oral therapy, found no differences in recurrent endometritis or other outcomes. There were no differences between groups for the outcomes of allergic reactions. The overall risk of bias was unclear in the most of the studies. The quality of the evidence using GRADE comparing clindamycin and an aminoglycoside with another regimen (compared with cephalosporins or penicillins) was low to very low for therapeutic failure, severe complications, wound infection and allergic reaction. The combination of clindamycin and gentamicin is appropriate for the treatment of endometritis. Regimens with good activity against penicillin-resistant anaerobic bacteria are better than those with poor activity against penicillin-resistant anaerobic bacteria. There is no evidence that any one regimen is associated with fewer side-effects. Following clinical improvement of uncomplicated endometritis which has been treated with intravenous therapy, the use of additional oral therapy has not been proven to be beneficial.

Plain-language summary: There were more treatment failures in women treated with an penicillin plus gentamicin (one study) compared with those treated with clindamycin plus gentamicin. Seven trials showed that an antibiotic treatment that had poor activity against bacteria resistant to penicillin had a higher failure rate and more wound infections than an antibiotic treatment that had good activity against these bacteria. There was no evidence that any of the antibiotic combinations had fewer adverse effects - including allergic reaction - than other antibiotic combinations. If the endometritis was uncomplicated and improved with intravenous antibiotics, there did not appear to be a need to follow the intravenous antibiotics with a course of oral antibiotics. Overall the reliability of the studies' results was unclear, the numbers of women studied were often small and data on other outcomes were limited; furthermore, a number of the studies had been funded by drug companies that conceivably would have had a vested interest in the results.