Canalization defects, namely subseptate or septate uteri, are significantly more common in women with miscarriage (5.3%), especially if this is combined with a history of infertility (15.4% ; Chan, 2011).
A septate uterus has generally been associated with the poorest reproductive performance, with fetal survival rates between 6 and 28% and abortion rates up to 80%. (Grimbizis et al., 2001) The finding of a septate uterus per se is not a mandatory indication for surgery because it is not always associated with a severe reproductive performance (Heinonen, 1982; Ashton,1988). Ludmir et al. (1990) have managed 42 patients with previously diagnosed but uncorrected uterine malformations: they have reported a 44% pregnancy loss before the 25 week of gestation, 8% premature deliveries, 48% term deliveries and a fetal survival rate of 53% in the septate group. Very similar to the latter are the data reported by Woelfer et al. (2001) in women with congenital anomalies detected incidentally by three-dimensional ultrasound. In this patient population considered at low risk of having an abnormal uterus, subseptate uterus is associated with first and second-trimester miscarriages in 45.6% of cases and preterm labor in 10.5% of cases. Nevertheless, the difference as against women with a normal uterus remains highly significant (Z = 4.68).
In a survey on women with untreated septate uterus (four studies between 1982 and 1997, pooled patients. Grimbizis et al. 2001), the authors have reported a mean 44.1% abortion rate, a mean 22.3% preterm delivery rate, a mean 32.9% term delivery rate and a mean 50% live birth rate. These data suggest that pregnancy outcome in patients with untreated septate uterus remains significantly lower than in women with a normal uterus, even though not so low as reported in other studies (Homer et al. 2000), and it is close to that of women with an untreated bicornuate uterus.
Nevertheless, mention has to be made that the term ‘untreated’ means a woman who have not undergone/will not undergo corrective surgery, so that we could suppose it is the reproductive performance of a mixed group of patients with either asymptomatic and symptomatic infertility or miscarriage.
On the other hand, if we look at most studies concerning hysteroscopic metroplasty for septate uterus in women with infertility or miscarriage, the results are totally different from those reported in unselected untreated patients, with a very poor reproductive performance before surgery. In one systematic review (Homer et al, 2000) on 1,062 pooled pregnancies from 658 patients the miscarriage rate before hysteroscopic metroplasty is 88%, preterm delivery rate is 9%, and term deliveries rate is 3%. In another review, (Grimbizis et al,2001) the data are very similar: out of 599 pooled pregnancies from 292 women the reported abortion rate is 86.4%, preterm delivery rate is 9.8%, term delivery rate 3.3% and live birth rate only 6.1%. Hence, we can suppose that in patients with a septate uterus who are symptomatic for infertility and/or miscarriage, wastage of the reproductive performance is an adverse reality.
Focusing on the most updated literature on the topic, we have found some remarkable studies published in the last ten years, which supports the poor reproductive performance of selected patients with a septate uterus prior to hysteroscopic surgery. Gergolet et al. (2012) has reported a miscarriage rate of 82.1%, an ectopic pregnancy rate of 2.1% and a live birth rate of 15.7%; Saravelos et al. (2007) have reached miscarriage, ectopic pregnancy and live-birth rates of 85.7%, 4.7% and 9.4%, respectively. Hollett-Caines et al. (2006) and Pace et al. (2006) have reported a nearly identical obstetrics history of their patients, with abortion premature labor rates around 95% and 5%. No data have been recorded on term delivery and live-birth rates, and we can presume it was nearly zero, as in the study by Venturoli et al.(2002) who reported a 100% abortion rate.
In conclusion, the review of the data seems to demonstrate a strong relationship between septate uterus and adverse reproductive outcome in selected patients with infertility and miscarriages.
Moreover, according to the systematic review and meta-analysis performed by Chan et al. (2011), canalization defects (septate and subseptate uteri) are associated with reduced clinical pregnancy rates (R.R. 0.86) and increased rates of first-trimester miscarriage (R.R. 2.89), preterm birth (R.R. 2.14) and fetal malpresentation (R.R. 6.24).
It is unclear whether the length of the uterine septum can have an impact on pregnancy outcome in women with a septate uterus. Kupesic and Kurjak (1998) have found no correlation between septal length and rate of obstetrics complications. Other authors suggest that pregnancy wastage, late first-trimester abortion or early second-trimester abortion could correlate with the length of the septum, with longer septae posing the highest risk (Valle et al., 2013). Nevertheless, most studies in the literature do not distinguish between septate and sub-septate uteri in terms of reproductive outcome, which means that patients under consideration are usually included in the same study group.
Recently Gergolet et al. (2012) have investigated prospectively whether hysteroscopic metroplasty in patients with a small septum could increase fertility and reduce the miscarriage rate as against metroplasty in a group of patients with a subseptate uterus that is having a septum of greater length. Both groups have shown very similar results: miscarriage rate respectively 94.9% and 82.1% before metroplasty vs. 11.1% and 14.0% after surgery; delivery rate 2.6% and 15.7% before metroplasty vs. 88.9% and 84.2% after the operation. The conclusion is that, according to the above results, there is no evidence to support that a small septum (indentation < 1.5 cm) has a different effect on the reproductive outcome as against a subseptate uterus (indentation of 1.5 cm or more), either before or after surgical correction of the anomaly. In other words, the septum length seems to be ineffectual in determining the reproductive performance of those patients, being a little septum as detrimental as well as a long one.
In a series of 826 deliveries from 730 women previously treated with hysteroscopic metroplasty, Tomazevic et al. (2007) have reported an improved pregnancy outcome after metroplasty both in the septate/subseptate uterus and small septate uterus (arcuate) groups. They have concluded that clinical behavior of a small septate uterus is not different from that of a septate uterus.
Woelfer et al. (2001) has found no correlation between the depth of fundal indentation in an arcuate uterus and first-trimester miscarriage, second-trimester miscarriage or preterm labor rates. In women with a subseptate uterus, the first-trimester miscarriage rate appears to decrease as the uterine septum length increases, but that finding has not reached statistical significance. Furthermore, there is no correlation between septum length and second-trimester miscarriage or preterm labor rates.
Therefore, further prospective controlled trials are needed in order to get to a definite conclusion on the issue, even though the most recent studies seem to contradict the importance of the internal indentation degree of the septum into the uterine cavity.