OVUM PICK-UP22

High-resolution ultrasound equipment with a vaginal transducer

The vaginal probe should have frequency of 5 to 7 MHz

Biopsy guide

Ovum pick-up (OPU) needle (any brand)

Ovum aspiration needle

15 ml poly round bottom IVF grade polystyrene falcon tubes.

3ml falcon pipettes

60 mm IVF plates

CO₂ incubator

Powder free sterile gloves

Vaginal probe cover

Heated platform

Sterozoom microscope

1ml BD syringes.

HEPES media/IVF media (Medicult/Cook/Vitrolife)

IVF grade oil.

Oocyte retrieval is performed approximately 36 hours after hCG injection, i.e. just before the time of ovulation.

Vagina is cleaned using normal saline. Approximately 500 ml of saline is required per case. Vaginal speculum is used to clear vaginal rugosities of the adherent secretions by gentle to and fro movements of the blade and clearing the debris with normal saline.

We recommend use of normal saline, which has been maintained at the 37^oC temperature.

Any ultrasound machine with the facility of transvaginal probe with a biopsy needle guide can be used. It is important that before commencing oocyte collection, the system is tested by aspirating282some culture medium. This also provides a column of fluid to collect the follicular fluid, thus encouraging laminar flow.

The collection tubes must be kept in a test tube warmer while they are waiting to be connected to the collection system. The tubes should not be filled above the level of alloy blocks and should be transported immediately to the embryologist.

It is my practice to always commence with the right ovary, and to aspirate all follicles sequentially. It is best to keep the needle within the ovary if possible, minimizing the amount of trauma to the ovarian capsule. When all follicles within the right ovary are aspirated, the needle is withdrawn from the vagina and the needle is flushed with medium to clear any blood. The pressure is retested, and the left ovary is then aspirated.

On transvaginal sonography ovarian follicles should be differentiated from other pelvic anatomical structures that may give the impression of being similar. Both, the preovulatory ovarian follicles and iliac vessels look hypoechoic (dark), and thus iliac vessels on cross section may be confused with a follicle.

The blood vessels can be differentiated by their minimal echogenic contents and by changing the plane of the transducer by 90°. The aim should be to view the vessels in the longitudinal view with ovaries lying in the plane adjacent to them. The bowel lumen is echogenic and will show peristaltic movements if observed for few seconds. Encysted peritoneal collections, hydrosalpinx and persistent ovarian cysts would have been documented on previous scans and do not cause any confusion.

Puncture of dermoid cyst and endometrioma should be avoided as they may spill the contents leading to localized chemical reaction and also serve as a nidus for pelvic infection. In situation where the ovaries are adherent and follicles cannot be approached, perforation of endometrial cavity should be avoided.

Needle is inserted in the biopsy guide fixed over the vaginal transducer, which has been covered with the sterile vaginal probe cover.

We flush the needle with HEPES based media to eradicate the dead space.

Transducer is inserted in the vagina and ovary is brought in the focus. We ensure that very minimal tissue lies between the follicles and the transducer. Follicle is focused in direction of biopsy guide probe line.

Needle is briskly inserted in the nearest follicle. The pressure within the follicle, before penetration, varies, depending on the size, shape, and position of the follicle. However, due to the pressure caused by the needle deforming the surface of the follicle at the time of puncture, the pressure within the follicle may be much higher.

The more blunt the needle, the higher the resultant pressure. Suction pressure should be on during this movement.

Negative suction during the time of entry ensures that even if fluid spills out during the time of entry, which is common with the blunt tip needle, fluid is aspirated and the oocyte cumulus complex is not lost in the peritoneal cavity.

Allow the suction to occur uniformly. Keep the needle tip under vision in the middle of the follicle. Always keep the pressure on and allow the follicle to collapse around the needle tip till the time follicle is completely emptied.

If the pressure was deactivated while the needle was still in the follicle the pressure within the needle and collecting tube drops, and there is, often backflow towards the follicle. This can result in the oocyte being sucked back and possibly lost. The amount of backflow depends on how much air enters the system and how much higher the collection tube is above the patient's pelvis.

It is therefore recommended that pressures be kept less than 120 mm Hg. The higher the speed of travel, the more chance of damage to the oocyte. Apart from the speed of travel, turbulent non-laminar flow can also damage the oocyte, either stripping its cumulus mass or fracturing the zona. It is believed that an intact cumulus may be important in preventing damage to oocytes.

Rarely fluid aspiration suddenly stops. Without wasting any times following steps should be carried out: