Endometrial recptivity

Benha University Hospital, Egypt Aboubakr Elnashar


Endometrial receptivity

Transcript of Endometrial recptivity

Page 1: Endometrial recptivity

Benha University Hospital, Egypt Aboubakr Elnashar

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1. Why?

2. What?

3. When?

4. How?

5. Effect of COH on endometrial receptivity

6. Effect of age on endometrial receptivity

7. Assessment of endometrial receptivity:

Functional markers: 1. Biochemical 2. Histological

Clinical assessment: 1.TVS 2. 3DUS 3.Doppler US

8. Improvement of endometrial receptivity

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The main causes of failure of IVF is

failure embryo implantation.

Embryo implantation depends on:

1.The quality of the embryo

2.Endometrial receptivity.

3. The embryo/endometrial interface Aboubakr Elnashar

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The onset of implantation is a successful

meeting of 2 separate processes: embryo

development & endometrial differentiation.

A synchrony between these functions is


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Understanding of

1.The mechanisms involved in this


2. How to assess? &

3. How to treat its disorders

represent the fundamental steps in the

improvement of IVF.

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Temporally unique sequence of factors

that make the endometrium receptive to

embryonic implantation

•The window of time when the uterine

environment is conductive to blastocyst

acceptance & subsequent implantation

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The endometrium is normally hostile

environment for an embryo , except

during implantation window.

Implantation window:

It is a period during which the

endometrium is optimally receptive to

implanting blastocyst

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Duration: 4 to 5 days

D6 to D10 postovulation, or

D7 to D11 post LH surge or

D20 to D24 of 28 D cycle

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Benefits of determining the implantation window:

It may be possible to

• Widen the implanation window by

manipulating the pre- & peri-implantation

endocrine environment

• Correlate endocrine, biochemical &

morphological changes with endometrial


• Recognize the time for ET that would best

correspond with the implantation window

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•Initiation of ER depend on: the down

regulation of endometrial PR & estrogen

receptors induced by P (Lindhard et al,2003).

•When the embryo has arrived in the

endometrial cavity: a preprogrammed

sequence of events occurs, which involves

the secretion of a multitude of biochemical

factors by the endometrium & the embryo,

leading to to the formation of a receptive

endometrium. Aboubakr Elnashar

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•Some factors like integrins like

v 3 make the endometrium

receptive & others like MUC1

make it resistant to implantation

except in small areas

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Abnormalities of the luteal phase

have been detected in all the

stimulation protocols on both

hormonal & endometrial levels.

COH adversely affect endometrial

receptivity (Devroey et al, 2004) Aboubakr Elnashar

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1. High concentration of estrogens & progesterone,

altered E2 to progesterone ratios.

2. Disturbed LH levels

3. Corpus luteum deficiency (Albano et al, 1998).

4. A direct effect of GnRh agonist or antagonist

on the corpus luteum or on endometrium

5. Altered endometrial receptivity from

endometrial asynchrony & earlier expression

of pinopodes Aboubakr Elnashar

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•Endometrial histology has revealed a wide

range of abnormalities during the various

ovarian stimulation protocols (Ubaldi et al, 1997).

In GnRh-agonist cycles, mid-luteal biopsies has


increased glandulo-stromal dyssynchrony

delay in endometrial development,

strong positivity of endometrial glands for PR,

decreased cell adhesion molecule profiles and

earliest appearance of surface epithelium

pinopodes (Soliman et al, 1994).

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These factors suggest a shift

forwards of implantation window.

Progesterone supplementation

improves endometrial histology, and

its necessity has been established, at

least in cycles, using GnRh agonists (Soliman et al, 1994).

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•There is increased peri-ovulatory P in

the COH cycles. The early rise of P has

a negative impact on endometrial

receptivity but not on oocyte-embryo

quality these cause premature

endometrial lutenization & provide an

explanation for the observed decrease

in endometrial receptivity (De long et al, 2000).

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On the other hand (Levi et al,2001).

Implantation & pregnancy rates did not

differ between IVF-ET patients and

recipients of donor oocytes.

Exposure of the developing

endometrium to COH during IVF

cycles does not inhibit embryo

implantation or affect pregnancy rate.

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•Embryo implantation rates declines in a linear


from 29% in women <34 yr to 5% at 42 yr (Rosenwaks et al,1995)

Oocyte senescence is responsible but demised

endometrial receptivity may play a role

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•Abnormal receptivity in aging subjects

is due to decreased levels of P receptors

promoted by the low levels of E2

receptors (Meldrum,1993).

However when the P dosage for luteal

support was increased, recipients aged

over 40 yr had a marked increase in

pregnancy rate

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On other hand:

No conclusive evidence of age related histological changes in the endometrium (Sauer et al,1993).

No difference in implantation, pregnancy,

miscarriage or live-birth rates between younger

& older patients (Abdalla et al,1997)

A study of 3 groups of women ranging from 25

to 60 yr found no difference in histology,

ultrasound, or steroid receptor content of the

endometrium between the different age groups (Fitzgerald et al,1993)

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I. Biochemical markers

II. Morphological markers

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I. Biochemical markers

1. Endometrial adhesion molecules


• 3 integrins are expressed by the endometrium

with a pattern that coincide well with the

window of implantation:


4 1 &

v 3 Aboubakr Elnashar

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•They are the best markers of endometrial

receptivity 1. They are co-expressed on glandular

epithelium only during cycle D 20 to 24

2. Most interest has been focused on the v 3

integrin since it appears in endometrial glands &

luminal surface on cycle days 20 to 21,

coincident with the opening of the window of


3. In endometriosis, v 3 expression is

reduced Aboubakr Elnashar

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4. Integrin expression in the endometrium allows

histologic dating for evaluation of endometrial


•Type I defect:

Failure to express v 3 integrin & out of phase

endometrium. P is effective

Type II defect (Occult endometrial receptivity defect) :

Failure to express v 3 integrin & in-phase


Mild endometriosis, hydrosalpinx, unexplained

infertility. Aboubakr Elnashar

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5. The expression of 4 & 3 on

peripheral blood lymphocytes may

correlate with endometrial cell integrin

expression during peak endometrial

receptive period.

So, it may be used as clinical markers

to assess endometrial receptivity (Reddy et


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2. Endometrial anti-adhesion molecules

Mucin 1

3. Endometrial Cytokines

Leukemia inhibitory factor



Colony-stimulating factor Aboubakr Elnashar

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4. Endometrial growth factors

Heparin binding-epidermal growth factor

Insulin like growth factor binding protein

5. Other endometrial markers

Mouse ascites Golgi (MAG)

Laminin, fibronectin & collagen IV


Cyclin E & p27 Aboubakr Elnashar

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Endometrial function tests:

The most efficient way to directly assess endometrial

receptivity (Kliman et al,1995).

1. MAG test:

Endometrial biopsy.

It measures a sticky mucinous substances that is secreted by

endometrial glands before implantation.

85% of normal fertile women express higher levels of MAG

between D 5 & D 18 & no expression after D19.

70% with unexplained infertility showed abnormal MAG

levels. Aboubakr Elnashar

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Delayed pattern: MAG expressed after


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2. Cyclin E & p27: It allows dating of the endometrium &

differentiating between normally & abnormally

developing endometrium.

Cyclin E:

First appears in proliferative phase &

not seen after D19


First appears on D17 & remains for the

rest of the cycle.

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Persistent expression of cyclin E

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B. Morphological markers

1. Pinopodes

• Globular protrusions in the surface

membrane of endometrial epithelial cells.

• Accurate markers of the implantation


• last for less than 2 days.

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• The timing of their formation depends on:

1. The hormone treatment applied

2. Patient's individual response.

On average, they form on

days 20-21 in natural,

days 19-20 in COH, and

days 21-22 in HC cycles

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• There is a wide (up to 5 days) variation

between women in the cycle days on

which pinopodes form. • Pinopode numbers correlate with implantation

[Nikas et al, 1996]

On other hand: there is evidence of

implantation occurring in the absence of

pinopodes (Redy et al.1997)

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In natural cycle:

There is an inherent synchrony between the

maturing endometrium & the developing

embryo, ensuring that both will meet at the right


Fully developed pinopodes have been detected

on days LH+6 to LH+9 (days 19 to 22) in

different individuals

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SEM of endometrial epithelium on day LH+4 of a natural cycle.

The secretory cells are bulging, covered with dense microvilli.

Ciliated cells are also seen Aboubakr Elnashar

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Day LH+7 of natural cycle: Most secretory cells bear fully developed

pinopodes, which may protrude beyond the length of the ciliated cells Aboubakr Elnashar

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Day 21 natural cycle: bulging decreases & small tips of microvilli

reappear on the membrane, which are now wrinkled (Regressing

pinopodes) Aboubakr Elnashar

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In COH- IVF cycles:

Embryonic development is probably

delayed because of the in vitro conditions

[Lopata,1996] while the endometrium may be

advanced [Nikas et al, 1999] resulting in an early

closure of the implantation window

before the zygote eventually reaches a

stage capable of initiating implantation.

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Accelerated pinopode formation correlated

strongly with preovulatory progesterone

rise (≥6 ng by day 13) [Develioglu et al, 1999]

Consequently, it would be highly desirable if the

window of receptivity in IVF cycles could be

postponed for a couple of days. A low dose of

mifepristone (antiprogestin) on days 14 and 15

caused delayed pinopode formation [Murphy et al,


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A strong correlation between pinopode

number and implantation success after

embryo transfer in a subsequent cycle.

The surface endometrial morphology

during the second cycle was found to be

similar to that in the first cycle Fully developed pinopodes were detected in

only one sample from each donor, indicating a

short life span.

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In Hormone –Controlled cycles:

The most receptive day of the cycle corresponds to fully

developed pinopodes or is postulated to be 1 day before

regressing or 1 day after developing pinopodes are observed.

A transfer cycle follows in which synchronization with the

embryo is arranged so that the predicted most receptive day

coincides with embryonic age day 6. It is assumed that by that

time the IVF embryo is ready to implant.

The use of SEM in monitoring endometrial differentiation and

timing of embryo transfer on an individual basis is


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Expression of

pinopodes in

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Shift of endometrial receptivity & blastocyst in IVF cycles as opposed to

natural cycles Aboubakr Elnashar

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2. Decrease in the epithelial tight junctions

between D13 & 23

3. Apoptosis

On D 19-20 apoptosis is detectable in the glands

of the basal layer

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Tight junction Apoptosis

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Potential functional markers are


invasive &

circumstantial Aboubakr Elnashar

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1. TVS: Thickness & pattern

Favorable receptivity: Trilaminar pattern (triple line),

Thickness:7-14 mm

Unfavorable receptivity:

Hyperechoic or isoechogenic,

Thickness<7 mm or >14 mm.

>14mm is not associated with reduced

receptivity (Ashkenzai et al,2002)

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Endometrial thickness:

has a significant positive correlation

with the duration of follicular

stimulation &

an inverse correlation with age.

Endometrial parameters are not reliable (Mital et al,2002)

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2. 3D US:

Endometrial volume:

2 ml is the minimum for a receptive


<1ml: no pregnancy (Ragaa et al,1999).

> 4 ml. No increase in ER

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3. Doppler US:

Some authors reported significant

correlation between pregnancy

rates & uterine artery Doppler flow

values (Carbillon et al,2001),

while others failed to show such a

relationship (Salle et al,1998)

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4. 3D power Doppler US:

Sub-endometrial perfusion can not

predict ER (Kuupesic et al,2001).

Use of subendometrial vascularization

index was superior in predicting the

pregnancy rate of IVF to using

endometrial volume (Ming et al,2003).

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5. MRI:

High cost, not used in routine practice

6. laser blood-flowmetry

A novel way to assess ER by measuring

endometrial tissue blood flow, using hystero

fiberscope laser blood-flowmetry.

It is superior to conventional parameters for

determining ER for implantation (Jinno et al,2001).

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Endometrial receptivity: practical dilemmas

1. There is doubt on the functional

importance of the morphological markers (Rogers et al,1996)

2. Despite the physiologic importance of the

events cited above, implantation can occur

under a wide range of morphological &

biochemical conditions.

All factors should be investigated

simultaneously, which is impractical Aboubakr Elnashar

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1.Tissue sampling, which is often

required for the direct assessment of

markers of endometrial receptivity, is

impossible in actual ET cycles.

It may cause trauma & bleeding at the

implantation site with potential

reduction in the chance of pregnancy.

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• On the other hand,

Ubaldi et al (1999) found that endometrial aspiration

biopsy at the time of egg collection did not

reduce pregnancy rates in women treated in


Recently, Olivennes et al (2003), confirmed that

uterine flushing on the day of egg

retrieval during an IVF-ET cycle did not

adversely affect pregnancy rates.

These results should be confirmed in a larger

sample of a prospective randomized study. Aboubakr Elnashar

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I. To develop ovarian stimulation protocols that

cause a minimum reduction in endometrial


II. To avoid the endometrium during stimulated

cycles altogether by freezing the embryos &

replacing them in subsequent natural cycles.

III. To improve uterine vascularization.

IV. To treat the pathology:

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I. To develop ovarian stimulation protocols

that cause a minimum reduction in

endometrial receptivity:

a. Ovarian stimulation protocols that do not use

clomiphene citrate

b. Correcting the endometrial alterations induced by

CC by vaginal supplementation of E2 & P (Elkind et

al, 2002)

c. Return to natural cycle IVF: the disadvantages of

working with a single developing follicle outweigh

any advantages gained (Yaron et al,1997)

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d. Exogenic 17estradiol during IVF cycles

significantly increases both implantation

rate & pregnancy rates & no difference in

the thickness of the endometrium (Kornilof et


e. Low dose of antiprogesterone may

correct the precocious lutenization &

restore endometrial receptivity (Paulson et al,1997)

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f. ‘Aromatse inhibitors:

Improving implantation rates in ART by reducing the

supraphysiologic levels of E2 associated with COH (Mitwally & Casper, 2001; Ziegler et al, 2004)

Endometrial morphology during the implantation

window in letrozole-stimulated cycles was

characterized by in-phase histological dating and

pinopode expression (Cortinez et al, 2005).

{E2 levels similar to spontaneous cycles and higher midluteal


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g. Switching the FSH stimulus

to that of LH (or mini HCG) in

the last stages of COH (Ziegler et al, 2004)

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II. To avoid the endometrium during stimulated

cycles altogether by freezing the embryos &

replacing them in subsequent natural cycles:

Not commonly used

a. Freezing protocols cause a loss in embryo

viability that negate any beneficial effect

b. Practical & financial considerations

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III. To improve uterine vascularization:

1. Low dose aspirin:

{inhibits the synthesis of thromboxane A2

without affecting the synthesis of

prostacyclin: increase blood flow velocity

in uterine & ovarian artery} (Rubinstein et al,1999).

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2. L-arginine (nitric oxide donor):

{NO is formed from arginine by NO synthetase

(Chwalisz et al,2000).

Relaxation of vascular smooth muscles of

endometrial vessels is mediated by NO}.

Oral L-arginine supplementation may

improve uterine blood flow, endometrial

receptivity & implantation rate

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3. Sildenafil citrate (viagra):

{is a phosphodiestrase inhibitor that prevents the

break down of cGMP (Cher et al, 2000).

NO relaxes vascular smooth muscles through cGMP}

Dose: 25 mg vaginally 4 times daily with the

beginning of COH until the day of HCG

Larger studies remain necessary to confirm their


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IV. To treat the pathology:

1. Luteal phase defect: Exogenous


2. Fibroids distorting the uterine cavity.

3. IU adhesions

4. Uterine septum

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5. Hydrosalpinx:

Negative effect on PR, IR, early pregnancy loss & live

delivery rate per ET.

{The fluid of hydrosalpinx:

constitute a mechanical barrier to implantation by

causing the embryo to float is deficient to support the developing embryo

toxic to the developing embryo Inflammatory response

Altered chemical composition of the tubal fluid: low K

& carbonate, proteins }(Lessey et al,1994).

Salpingectomy resulted in improvement of outcomes (NICE, 2004)

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6. Endometriosis: Prolonged pituitary

down regulation (Marcus et al,1994).

7. Autoimmune conditions:

prednisolone & low dose aspirin:

increase both implantation &

pregnancy rate (Birkenfield et al,1994)

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Benha University Hospital, Egypt

Aboubakr Elnashar