Assisted Reproductive Technology (ART): IVF, ICSI & IUI Explained

In short: Assisted reproduction is a group of medical procedures that help couples achieve pregnancy. The simplest is to prepare and concentrate the sperm in the laboratory and place it in the uterus at a time set by ultrasound monitoring. It is used for blocked tubes, irregular ovulation and polycystic ovaries, semen problems and unexplained infertility; the doctor chooses the most suitable method for each couple.

Assisted Reproductive Technology (ART) refers to a group of medical techniques that help couples facing fertility challenges achieve a pregnancy. ART can also be used in certain situations where genetic concerns are present. In general, these methods involve selecting healthy sperm in the laboratory and placing it near the woman’s egg at the time of ovulation — either inside the uterus, the fallopian tubes, or directly into the ovarian follicle. In some cases, the egg is retrieved from the ovary and fertilized outside the body, in a process known as In Vitro Fertilization (IVF).

If you and your partner are exploring fertility treatment, understanding these options can help you feel more confident discussing them with your doctor.

Who Can Benefit from Assisted Reproductive Technology?

ART may be recommended for couples with:

• Endometriosis.
• Irregular ovulation, such as in polycystic ovarian syndrome (PCOS).
• Abnormal semen analysis results.
• Other fertility-related conditions identified by your physician.
• Cervical factors, such as thickened mucus or the presence of sperm antibodies.
• Unexplained infertility.
• Blocked or damaged fallopian tubes.
• Women between 35 and 40 years of age.
• Men with anti-sperm antibodies.

How Semen Is Prepared for ART

Several laboratory techniques can be used to prepare semen for fertility treatment. Since IVF was first introduced, researchers have continued refining these methods to improve outcomes.

Sperm washing removes substances that could cause irritation inside the uterus. Bacteria, white blood cells, and non-motile sperm — which can interfere with fertilization — are separated from the seminal fluid. When needed, special laboratory additives may be used to support sperm motility and improve the chances of successful fertilization.

Before preparation, the embryology team evaluates the sperm’s ability to fertilize an egg. The goal is to reach an accurate diagnosis, address any issues with sperm production or function where possible, and give the sperm the best possible chance of achieving a healthy pregnancy.

Types of Assisted Reproductive Technology

Fertility science has evolved considerably over the past decades. Some of the techniques below were developed in the early years of ART and are rarely used today, having largely been replaced by IVF and ICSI. They are described here for educational purposes, so you can better understand how modern fertility treatment developed.

Fallopian Tube Sperm Perfusion (FSP)

In this technique, a larger volume of prepared semen (around 4 ml) is placed into the uterus so that it can reach the fallopian tubes, compared to the smaller volume (about 0.3–0.8 ml) used in intrauterine insemination (IUI). Some researchers believed this wider distribution of sperm might improve pregnancy chances, though study results have varied. Whether IUI or FSP is more suitable depends on individual circumstances and should be discussed with your physician. The indications and technique are otherwise similar to IUI.

Trans-vaginal Intra-Fallopian Insemination (TVIFI)

A thin catheter is guided through the cervix to reach the fallopian tube, where sperm is then placed directly. The aim is to deliver sperm as close as possible to the natural site of fertilization.

Direct Intra-Fallopian Insemination (DIFI)

Also called Direct Intra-Follicular Insemination: using trans-vaginal ultrasound guidance, sperm is injected directly into the ovarian follicle within the ovary. This historical method is no longer used.

Gamete Intra-Fallopian Transfer (GIFT)

Introduced in 1984, this method involves stimulating the ovaries with fertility medication so that several eggs mature. The eggs are then collected and placed together with prepared sperm directly into a fallopian tube, allowing fertilization to occur naturally inside the body. If successful, the fertilized egg travels toward the uterus and implants in the uterine lining. The entire procedure, from egg retrieval to placement in the tube, typically takes around 30–60 minutes and may be performed by laparoscopy or trans-vaginal ultrasound guidance.

• This method was generally considered for:
• Women with healthy, open (patent) fallopian tubes.
• Women with endometriosis, provided the fallopian tubes were healthy.
• Men with low sperm counts (oligospermia), where retrieved eggs were mixed directly with prepared sperm.

Zygote Intra-Fallopian Transfer (ZIFT)

ZIFT is similar to GIFT, but fertilization happens in the laboratory (as in IVF) rather than inside the fallopian tube. Once fertilization is confirmed, the resulting zygote is transferred into a healthy fallopian tube, where it continues its natural development and travels toward the uterus for implantation.

Because pregnancy outcomes with GIFT tended to be lower in cases involving abnormal semen — and because it was harder to confirm whether fertilization had actually taken place — researchers developed ZIFT as a refinement that allows fertilization to be verified in the lab first.

Tubal Embryo Transfer (TET) and Pronuclear Stage Transfer (PROST)

These names describe the same general approach, differing only in the developmental stage of the embryo at the time of transfer. The process begins with ovarian stimulation, followed by egg retrieval and laboratory fertilization with prepared sperm. The resulting embryo is then transferred into the fallopian tube, similar to the ZIFT method, where it continues developing naturally on its journey to the uterus.

• What is the difference between TET, TUFT, PROST, and ZIFT?

All four methods follow the same general steps: ovarian stimulation to develop mature follicles, an hCG trigger injection at the right time, egg retrieval by trans-vaginal ultrasound, and fertilization in the laboratory.

The key difference lies in the embryo’s developmental stage at the time of transfer. In ZIFT and PROST, the fertilized egg is transferred to the fallopian tube at the pronuclear stage, roughly 18 hours after sperm exposure. In TUFT and TET, the transfer happens slightly later, once the fertilized egg has divided into two or more cells — known as a “pre-embryo.”

These approaches were sometimes considered in cases of male infertility, since they allowed the egg to be exposed to a larger number of sperm and permitted early development to be monitored in the lab, unlike the original GIFT technique.

Unlike IVF, where the embryo is transferred into the uterus, these four methods placed the fertilized egg into the fallopian tube. Because they usually required laparoscopy and did not give better results than modern IVF with uterine transfer, they are no longer used. Published pregnancy rates for these historical techniques were reported in the range of roughly 17–37% per cycle, though these figures come from older studies and modern IVF/ICSI outcomes are generally reported separately.

Direct Intra-Peritoneal Insemination (DIPI)

In this method, prepared sperm is placed through the vaginal wall into the “pouch of Douglas” (a space near the ovaries), about 36 hours after the hCG trigger injection. It is a relatively simple, clinic-based procedure that was sometimes considered for couples with unexplained infertility, cervical factors, or a lower sperm count. Reported pregnancy rates in the literature were around 10–20%.

Peritoneal Oocyte and Sperm Transfer (POST)

After ovarian stimulation and an hCG trigger, several mature eggs (typically 3–4) are retrieved and placed together with prepared sperm into the pouch of Douglas, near healthy fallopian tubes. This method was sometimes used for couples with unexplained infertility or sperm antibody issues, with reported pregnancy rates in the literature around 20–25% per cycle.

Direct Oocyte and Sperm Transfer (DOST)

This approach combines ovarian stimulation, egg retrieval, and sperm preparation. After retrieval, eggs are incubated in culture media for several hours before sperm is added. Once early signs of fertilization are observed (sperm binding to the egg’s outer membrane), a small number of eggs — typically around three — are transferred into the uterus using the same type of catheter used in standard IVF embryo transfer.

Trans-uterine Fallopian Transfer (TUFT)

In this technique, a very thin catheter is passed through a second catheter that crosses the uterus, allowing the fertilized egg to be delivered directly into the fallopian tube.

Modern ART Methods Used Today

Advances in reproductive medicine mean that most of the historical techniques above have been replaced by more effective, better-studied methods. The ART treatments most commonly used today include:

Intrauterine Insemination (IUI), usually combined with mild ovarian stimulation

• In Vitro Fertilization (IVF)
• Intracytoplasmic Sperm Injection (ICSI)
• Intracytoplasmic Morphologically Selected Sperm Injection (IMSI) – a high-magnification sperm selection technique that may be considered in selected cases; current evidence (ESHRE 2023) does not show a routine benefit over standard ICSI
• Preimplantation Genetic Testing (PGT, formerly called PGD) for couples who carry a known genetic or chromosomal condition
• Selecting the Sex of the Baby

Every fertility journey is different, and the right ART approach depends on your specific diagnosis, medical history, and goals. If you have questions about IVF, ICSI, IUI, or any other fertility treatment, the team at Dr. Najeeb Layyous’s clinic is here to guide you through your options with clear, personalized advice.

Dr. Najeeb Layyous, FRCOG

Consultant Obstetrician, Gynecologist and Infertility Specialist