The septate uterus is the most common structural uterine anomaly [56] and is caused by an incomplete resorption of the partition between the fused Mullerian ducts. The diagnosis can be made by HSG with accuracy between 20–60 % and together with an ultrasound examination the diagnostic accuracy improves to 90 % [60]. It is difficult to distinguish between bicornuate uterus and septate uterus by HSG alone as the uterine fundus is not visualised. Transvaginal ultrasound has a sensitivity of 100 % and specificity of 80 % in the diagnosis of the septate uterus [61]. Three-dimensional (3D) ultrasound (92 % sensitivity) [62] and magnetic resonance imaging (MRI) (100 % sensitivity) can also be used as a diagnostic tool [61]. However, the gold standard is hysteroscopy and laparoscopy.

Among the different types of uterine anomalies, the septate uterus is associated with the poorest reproductive outcome. The septate uterus maybe associated with pregnancy loss [63] and infertility [64].

Unicornuate uterus results from a fusion defect of the Mullerian ducts with one cavity being normal with a fallopian tube and cervix, whereas disrupted development is seen in the other horn. The other horn can be completely absent or rudimentary with or without a cavity that may connect to the primary horn. 40 % of women with a unicornuate uterus have an associated urinary tract anomaly [66].

Unicornuate uteri are more common in women with infertility and miscarriage than the general population. Furthermore, they are associated with poor obstetric outcome with a live birth rate of only 29.2 %, prematurity rate of 44 %, miscarriage rate of 29 %, and ectopic pregnancy of 4 % [67]. Another review of 151 women with a unicornuate uterus had 260 pregnancies and a mean miscarriage rate of 37.1 %, mean preterm delivery rate of 16.4 % and the mean term delivery rate of 45.3 % [68]. However, different types of unicornuate uterus are associated with different reproductive outcomes depending on the vascular supply, muscular mass of the myometrium and degree of cervical competence.

The rudimentary horn can contain functional endometrium which can lead to endometriosis, haematometra, pelvic pain and pregnancy with a risk of uterine rupture. Therefore, removal of the uterine horn containing endometrium by laparoscopy or laparotomy is recommended. However, there is no evidence that removal of the rudimentary horn improves reproductive outcome.

The bicornuate uterus results from an incomplete fusion of the two Mullerian ducts and is a common uterine anomaly (46.3 %) [57].

Bicornuate uteri are more common in women with infertility and miscarriage than the general population. Women with a bicornuate uterus are at increased risk of second trimester miscarriage and preterm birth. They usually do not need any surgical intervention. The mildest form of the bicornuate uterus is the arcuate uterus and does not necessitate surgery. A systematic review showed an increased rate of second trimester miscarriage and fetal malpresentations at delivery in women with an arcuate uterus [69].

Complete failure of fusion of the two Mullerian ducts results in the uterus didelphys with a duplication of uterus and cervix and sometimes bladder, urethra, vagina and anus [70]. The uterus didelphys is more common in infertile women and women with a miscarriage than the general population. There is an increased risk of preterm birth and fetal malpresentations [68].

The volume of menstrual bleeding can indicate the reproductive prognosis as it tells how much healthy endometrial tissue is present. Women with this condition can present with amenorrhoea, hypomenorrhoea, dysmenorrhoea, recurrent pregnancy loss and infertility [76, 77]. Poor implantation following ART and abnormal placentation has been reported in women with intrauterine adhesions [76].

Hysteroscopy is the gold standard for diagnosis and treatment of intrauterine adhesions. Hysteroscopic adhesiolysis with scissors, electrosurgery or laser can restore the size of the uterine cavity. Severe intrauterine adhesions may require multiple operations. The division of adhesions can be performed under ultrasound or laparoscopic guidance to prevent perforation of the uterus. Other complications of the procedure include haemorrhage and infection. The reformation of adhesions seems to be related to the severity of the adhesions. There are a number of surgical and hormonal approaches in order to prevent postoperative adhesion formation. Estrogen is used to help with endometrial proliferation following the procedure [78]. An intrauterine placement of a device helps with the mechanical separation of the endometrial walls. This can be in the form of an intrauterine copper coil or an intrauterine triangular balloon [78, 79]. Furthermore, adhesion barriers such as hyaluronic acid seem to be promising. A systematic review looked at the effect of anti adhesion barrier gels following operative hysteroscopy and could find a reduction in adhesions at second look hysteroscopy 3 months later [80]. The postoperative assessment of the uterine cavity after adhesiolysis is recommended 1–2 months following the initial surgery and can be in the form of a midcycle ultrasound to measure the endometrial thickness, HSG and hysteroscopy [81]. Early recognition of recurrence of adhesions is important to achieve the best outcome and reduce obstetric risks [78].

An overall pregnancy rate from 40 to 63 % has been reported following adhesiolysis [77, 82–84]. More recently, intrauterine adhesion treatment with resectoscope or versapoint with subsequent hormone therapy and intrauterine copper coil placement showed to have an overall live birth rate of 41 % [83].

The reproductive outcome is dependent on the menstrual pattern, the severity of the adhesions and recurrence following treatment [85]. Nevertheless, pregnancies following treatment of intrauterine adhesions are at high risk of spontaneous miscarriage, preterm delivery, intrauterine growth restriction, abnormal placentation or uterine rupture and require careful monitoring [76].

Endometriosis is a chronic inflammatory condition. Moderate to severe endometriosis can lead to anatomical changes and thereby impair fertility. However, it is less clear how minimal to mild endometriosis interferes with fertility.

It has been suggested that ovulation, oocyte pick up by the fallopian tubes, fertilisation, embryo transport and implantation maybe disrupted in women with endometriosis [96].

Hormonal medical treatment with progestins, oral contraceptives and gonadotropin releasing hormone agonists suppresses ovulation and menstruation and is not suitable for women seeking fertility. A Cochrane review showed that hormonal treatment in women diagnosed with minimal-mild endometriosis does not improve spontaneous conception [97, 98]. However, surgical treatment of minimal-mild endometriosis increases spontaneous conception rates compared to diagnostic laparoscopy (OR 1.64, 95 % CI 1.05–2.57) [99, 100]. Surgical treatment of infertile women with moderate to severe endometriosis also increases spontaneous pregnancy rates when compared to expectant management [101]. Surgery for deep infiltrating endometriosis is mainly performed to alleviate pain, but carries risk of major complications like ureteral and rectal injuries [102]. Furthermore, it may not greatly improve reproductive outcome [103]. Surgical treatment of endometriosis aims to remove visible endometriosis and restore the anatomy.

Assisted reproductive technology (ART) can be offered to infertile women with endometriosis. Stimulated IUI treatment in women with minimal to mild endometriosis maybe considered as it increases live birth rates compared to expectant management [104]. However, the most recent NICE guideline on fertility does not recommend routine IUI treatment in women with mild endometriosis [105]. They recommend IVF treatment after a total of 2 years without conception. IVF treatment is offered to women with endometriosis as it overcomes anatomical distortion and the abnormal peritoneal environment. Nevertheless, the pregnancy rates are lower compared to women with tubal factor infertility and women with severe endometriosis have even lower pregnancy rates than women with mild endometriosis [106]. A systematic review looked at the effect of endometriosis on IVF outcome and reported reduced fertilisation rates in women with stage I/II endometriosis (RR = 0.93, 95%CI 0.87–0.99) [107]. Women with stage III/IV endometriosis had low implantation (RR = 0.79, 95%CI 0.67–0.93) and clinical pregnancy rates (RR 0.79, 95%CI 0.69–0.91) [108]. Nonetheless, prolonged down-regulation with GnRH agonist 3–6 months prior to IVF improves clinical pregnancy rates as confirmed by a meta-analysis of three randomized trials [108].

The management of endometriomas depends on factors like size and previous ovarian surgery. Conservative treatment of endometrioma maybe considered with a small size (<3 cm). Surgical excision of endometrioma may lead to damage of healthy ovarian tissue and can reduce the ovarian reserve [109, 110]. Therefore, surgery should be avoided in women with previous ovarian surgery. Surgical treatment may be considered in women with large endometriomas (>3 cm) to improve endometriosis-associated pain or accessibility during egg collection for IVF treatment [111]. Laparoscopic excision of endometrioma is the preferred treatment as it has a lower recurrence and higher spontaneous pregnancy rate compared to drainage or coagulation of the endometrioma [112]. Furthermore, cystectomy gives a histological diagnosis. When the endometrioma is very large a two step procedure (surgery followed by 3 months GnRH agonist treatment and repeat surgery) may be considered. Medical management in the form of GnRH analogue can reduce the size of the endometrioma. A study showed that the presence of endometrioma affected the number of oocytes collected for IVF treatment, but oocyte quality or clinical pregnancy rate was not affected when compared to women without endometrioma [113]. Studies have demonstrated that there is no cumulative recurrence risk of endometriosis following assisted reproductive technology (ART) [114–116].

Overall it is important to take into account the benefits and risks of surgery, medical treatment and ART when managing couples with endometriosis associated infertility.

Multiple factors could be contributing to the pathogenesis of adenomyosis. One theory is that the basal layer of the endometrium invaginates between smooth muscle cell bundles or along lymphatic vessels into the myometrium [124]. Another theory is that adenomyosis may develop de novo through metaplasia of Mullerian remnants [125]. The relationship between adenomyosis and fertility is not exactly clear. On one hand adenomyosis is found in multiparous women and on the other hand it is seen in women with infertility and miscarriages [126].

Medical and surgical treatments are available. Medical treatment is in the form of NSAIDs, progestogens and GnRH agonists. Women undergoing IVF treatment benefit from long agonist stimulation protocols with GnRH agonists [127]. However, women with adenomyosis had a lower clinical pregnancy rate on the antagonist cycle compared to women without adenomyosis (OR 0.4, 95%CI 0.18–0.92) [128]. A systematic review about adenomyosis and IVF outcome showed a 28 % reduction in the likelihood of a clinical pregnancy following IVF/ICSI [117].

It has been shown that implantation, pregnancy, and live birth rates are reduced by 50 % in women with hydrosalpinx [129–131]. Furthermore, miscarriage rates are doubled [130]. The presence of hydrosalpinx fluid in the uterine cavity is embryotoxic and alters the embryo endometrium receptivity as well as the tubo-uterine flow dynamics [132, 133].

The management of hydrosalpinges involves the disruption of the tubo-uterine communication. A randomised controlled trial found that women following laparoscopic salpingectomy for hydrosalpinx prior to IVF doubled their live birth rates compared to women without surgery [134]. This interrupts the communication between the fallopian tube and the uterine cavity. A systematic review confirmed a doubling of clinical pregnancy rates following surgical treatment of hydrosalpinges (OR 2.14, 95 % CI 1.23–3.73) [135]. However, salpingectomy can reduce the blood supply to the ovary and thereby reduce the ovarian reserve. Studies looking into the ovarian response during IVF treatment did not show a significant difference in women who had a previous salpingectomy [136, 137]. If the surgical skills are present the tubal mucosa could be assessed and if found to be healthy a salpingostomy could be attempted. These patients need to be informed about the risk of an ectopic pregnancy. Laparoscopic tubal occlusion is possible if there are severe pelvic adhesions present. A systematic review confirmed a significant increase of pregnancy rates following this approach [135]. Laparoscopic tubal occlusion is as effective as laparoscopic salpingectomy in improving clinical pregnancy rates (RR 1.1, 95%CI 0.85–1.6) [138].

Hysteroscopic occlusion of the tube with the help of Essure® (Bayer, Whippany, NJ, USA) can be considered in women when laparoscopy is contraindicated. Essure® is a 4 cm long microinsert with polyethylene terephthalate fibres that induce a tissue reaction resulting in tubal occlusion. It is used for hysteroscopic tubal sterilisation. Initially there were concerns about the possible effect of the coils from the Essure® device protruding into the uterine cavity on implantation and pregnancy [139]. However, a study assessed the pregnancy outcome of 50 pregnancies following Essure® insertion and concluded that the device is unlikely to interfere with implantation and pregnancy [140]. A systematic review looked into the efficacy of Essure in the management of hydrosalpinx before IVF and found a 27.9 % live birth rate per embryo transfer (95 % CI 21.7–36.6 %) [141]. It appears that Essure ® is an effective treatment option for women with hydrosalpinges before IVF when the laparoscopic approach is contraindicated.