Fertility / The woman / Female internal reproductive organs

Female internal reproductive organs

You will have ultrasound scans during your treatment which will provide information about your womb, fallopian tubes, ovaries, etc. You can read more about the female internal reproductive organs, all of which have their own influence on fertility, here.

The female internal reproductive organs consist of the vagina, the womb and cervix, the fallopian tubes and the ovaries.

The womb's job is to receive the fertilised egg, nourish the foetus as it develops and assist in the birth of the baby. It mainly consists of muscle tissue and has an inner mucous membrane lining called the endometrium. When the woman is not pregnant, the shape and size of the uterus resembles a small pear; it is approximately 8-10 cm long and weighs 50-100 g. The uterus grows during pregnancy, and by the due date it weighs around 1000 g. After delivery, it returns almost to its normal size. After the menopause, the uterus normally becomes slightly smaller.

In most women, the womb tilts forwards, but it is not abnormal for some women if their womb tilts backwards, while in others it is upright. The position of the womb has no bearing on the chances of becoming pregnant. The womb is supported by the pelvic floor muscles. The upper rounded part is called the uterine cavity while the narrow part is called the cervix.

The uterine cavity is lined with the endometrium, which is affected by the varying levels of sex hormones in the body. During a menstrual cycle, the endometrium undergoes various phases due to the influence of the varying levels of sex hormones produced in the ovaries.

A menstrual cycle commences on the day on which the woman experiences the first bleed. This bleed is due to the lining of the uterus being shed because no fertilised egg has become implanted in the endometrium. When the endometrium is shed, a new one is formed that gradually thickens. Around the time of ovulation, the endometrium prepares to receive a fertilised egg, which can then implant and continue its development. If the egg is not fertilised, the endometrium will be shed and another menstrual period will begin. This process is repeated every month until the menopause. After the menopause, the endometrium thins and is no longer shed. This causes the periods to stop.

The cervix

The cervix is approximately 2 cm in diameter and about 3 cm long and forms the passage between the uterine cavity and the vagina. The cervix is situated below the womb and down into the vagina, and the lowest part of it can be both seen and felt during a gynaecological examination. A catheter is passed through the cervical canal during insemination or when placing fertilised eggs back in the womb. The thin catheter (containing either sperm for insemination or fertilised eggs during IVF) is easiest to insert when the woman has a full bladder for this part of the treatment. This is because the curvature of the cervical canal is straightened when the bladder is full.

The ovaries produce sex hormones and contain small primordial follicles. Usually, only one egg ripens and is released (ovulation) from the ovaries during each cycle. Ovaries normally come in pairs and are the female equivalent of the testicles in males. The ovaries are oval in shape and measure approximately 3 x 1.5 x 1.5 cm. They are situated in the pelvis close to the womb and fallopian tubes.

The ovaries are always scanned during IVF or hormone-stimulated insemination. This is done to check how active the ovaries are and to ensure that there are no cysts.

As well as producing, storing and releasing ripe eggs while the woman is fertile, the ovaries also act as endocrine glands by producing sex hormones, primarily oestrogen, progesterone and androgens.

The fallopian tubes are two narrow tubes linking the ovaries to the uterus. They are approximately 0.5-10 mm in diameter (although this varies along the length of the tubes) and about 10-12 cm long. After ovulation, the ripe egg moves from the ovary to the uterus via the fallopian tube. Fertilisation normally takes place in a fallopian tube. If the fallopian tubes are blocked, the egg and the sperm cells cannot meet – and the egg will not be fertilised. The same can happen if the fallopian tubes are partly blocked. If the fallopian tubes are partly blocked, there is a greater risk of ectopic pregnancy. 

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Stork IVF Klinik | St. Kongensgade 40 H, 1. sal | DK-1264 Copenhagen K
Tel. +45 3257 3316 | Fax +45 3257 3346 | info@storkklinik.dk | CVR. No. 33 03 49 11

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